Flow path control device and vehicle height adjustment apparatus

ABSTRACT

A flow path control device according to one embodiment includes a first valve, a unit main body and a control valve. The unit main body has an accommodation portion, a first radial communication hole and a side recess portion. The accommodation portion is recessed from a chamber accommodating the oil to cause the first valve to close the first radial communication hole. The side recess portion is recessed from the chamber so as to be continuous to the accommodation portion and not to be continuous to the first radial communication hole. The control valve is movable in the accommodation portion of the unit main body between a position at which a groove of the control valve communicates with the side recess portion and the first radial communication hole and a position at which the groove does not communicate with them.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from Japanese Patent Application No.2016-071268 filed on Mar. 31, 2016, the entire contents of which areincorporated herein by reference.

BACKGROUND

Technical Field

The present invention relates to a flow path control device and avehicle height adjustment apparatus that adjusts the vehicle height of amotorcycle.

Related Art

In recent years, there is proposed an apparatus that increases thevehicle height of a motorcycle while traveling and decreases the vehicleheight in order for a driver to easily get on and off the motorcycle ata stop.

For example, a vehicle height adjustment apparatus disclosed inJP-B-H08-22680 automatically changes the vehicle height of a motorcyclein response to the vehicle speed of the motorcycle. The vehicle heightadjustment apparatus automatically raises the vehicle height when thevehicle speed reaches a set speed, and automatically lowers the vehicleheight when the vehicle speed reaches a vehicle speed which is lowerthan or equal to the set speed. More specifically, when a switch isautomatically turned on when the vehicle speed reaches the set speed andan electromagnetic actuator operates, when the vehicle speed reaches theabove-described vehicle speed, an adjustment valve body is pushed out,and according to this, communication between a secondary side oilchamber and a primary side oil chamber which communicate with an oilchamber of a cylinder is blocked, and thus, discharge oil from a pump ispressurized from the primary side oil chamber to a working oil chambervia a through oil path. Due to this, a spring seat is pushed down, andaccording to this, the vehicle height is raised. In addition, when theswitch is automatically turned off when the vehicle speed reaches avehicle speed which is equal to or lower than the set speed, theadjustment valve body is attracted, the primary side oil chambercommunicates with the secondary side oil chamber, and thus, working oilin a working oil chamber returns to the oil chamber of the cylinder viathe primary side oil chamber and a passage, and the vehicle height islowered.

SUMMARY

In a case where a valve which switches a flow path of a fluid, such asoil (working oil), is used, it is desirable to control the valve to beoperated with high accuracy.

The invention provides an apparatus which can operate the valve withhigh accuracy.

According to an aspect of the invention, a flow path control deviceincludes a first valve, a flow path forming member, and a second valve.The first valve opens and closes a first flow path in which a suppliedfluid is oriented toward a first chamber. The flow path forming memberis formed with a first recess portion, a communication path, and asecond recess portion. The first recess portion is recessed from asecond chamber accommodating the fluid that applies a force in adirection in which the first valve is closed to the first valve. Thecommunication path communicates with the first recess portion and thefirst chamber. The second recess portion is recessed from the secondchamber so as to be continuous to the first recess portion and not to becontinuous to the communication path. The flow path forming member formsa second flow path oriented toward the first chamber from the secondchamber via the communication path and the second recess portion. Thesecond valve is formed with a groove which is recessed from an outersurface. The second valve is fitted to the first recess portion of theflow path forming member. The second valve opens and closes the secondflow path by moving between a position at which the groove communicateswith the second recess portion and the communication path and a positionat which the groove does not communicate with the second recess portionand the communication path.

In addition, according to another aspect of the invention, a vehicleheight adjustment apparatus includes a first valve, a flow path formingmember, and a second valve. The first valve opens and closes a firstflow path in which a fluid supplied from a pump is oriented toward astorage chamber which stores the fluid. The flow path forming member isformed with a first recess portion, a communication path, and a secondrecess portion. The first recess portion is recessed from a backpressure chamber accommodating the fluid that applies a force in adirection in which the first valve is closed to the first valve. Thecommunication path communicates with the first recess portion and thestorage chamber. The second recess portion is recessed from the backpressure chamber so as to communicate with the first recess portion andso as not to communicate with the communication path. The flow pathforming member forms a second flow path oriented toward the storagechamber from the back pressure chamber via the communication path andthe second recess portion. The second valve is formed with a grooverecessed from an outer surface. The second valve is accommodated in thefirst recess portion of the flow path forming member. The second valveopens and closes the second flow path by moving between a position atwhich the groove communicates with the second recess portion and thecommunication path and a position at which the groove does notcommunicate with the second recess portion and the communication path.

According to the invention, it is possible to operate the valve withhigh accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a schematic configuration of a motorcycleaccording to an embodiment.

FIG. 2 is a sectional view of a front fork according to the embodiment.

FIG. 3A is a view schematically illustrating an open and closed state ofa flow path in a case where a front wheel side flow path switching unitis in a first switch state.

FIG. 3B is a view schematically illustrating an open and closed state ofthe flow path in a case where the front wheel side flow path switchingunit is in a second switch state.

FIG. 3C is a view schematically illustrating an open and closed state ofthe flow path in case where the front wheel side flow path switchingunit is in a third switch state.

FIG. 3D is a view schematically illustrating an open and closed state ofthe flow path in case where the front wheel side flow path switchingunit is in a fourth switch state.

FIG. 4 is an enlarged view of a portion IV in FIG. 2.

FIG. 5 is an enlarged view of a portion V in FIG. 4.

FIG. 6 is a perspective view of an upper end side columnar portion of aunit main body.

FIG. 7A is a view illustrating a state where a position of a groove of acontrol valve in an axial direction and a position of a first radialcommunication hole overlap each other.

FIG. 7B is a view illustrating a state where the position of the grooveof the control valve in the axial direction and the position of thefirst radial communication hole do not overlap each other.

FIG. 8 is a view illustrating an operation of a front fork during acompression stroke.

FIG. 9 is a view illustrating the operation of the front fork during anextension stroke.

FIG. 10 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit is in the first switch state.

FIG. 11 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit is in the second switch state.

FIG. 12 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit is in the third switch state.

FIG. 13 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit is in the fourth switch state.

FIG. 14 is a view illustrating a positional relationship between anouter circumferential surface of the control valve and an openingportion of a first radial communication hole in a case where the grooveis at a position which does not communicate with a side recess portionand the first radial communication hole.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment will be described in detail with reference tothe accompanying drawings.

FIG. 1 is a view illustrating the schematic view of a motorcycle 1according to the embodiment.

The motorcycle 1 includes a front wheel 2 that is a wheel on a frontside; a rear wheel 3 that is a wheel on a rear side; and a vehicle mainbody 10 that has a vehicle body frame 11 which is a frame of themotorcycle 1, a handle bar 12, an engine 13, a seat 19, and the like.

In addition, the motorcycle 1 has a front fork 21 as an example of asuspension apparatus which links the front wheel 2 to the vehicle mainbody 10. In addition, the motorcycle 1 has a rear suspension 22 whichlinks the rear wheel 3 to the vehicle main body 10. In addition, thefront fork 21 and the rear suspension 22 are an example of a changingdevice which changes a relative position of the vehicle main body 10 andaxles of the front wheel 2 and the rear wheel 3.

The motorcycle 1 includes two brackets 14 and a shaft 15. The brackets14 hold the front fork 21 disposed on the right side of the front wheel2 and the front fork 21 disposed on the left side of the front wheel 2,and the shaft 15 is disposed between the two brackets 14. The shaft 15is rotatably supported by the vehicle body frame 11.

The motorcycle 1 includes a control device 70 that controls the vehicleheight of the motorcycle 1 by controlling a front wheel side flow pathswitching unit 300 that will be described later of the front fork 21.

Configuration of Front Fork 21

Hereinafter, the front fork 21 will be described in detail.

FIG. 2 is a sectional view of the front fork 21 according to theembodiment.

The front fork 21 according to the embodiment is a so-called uprightfront fork that is disposed between the vehicle main body 10 and thefront wheel 2 of the motorcycle 1, and supports the front wheel 2 side,and in which an outer member 110 (which will be described later) isdisposed close to the front wheel 2, and an inner tube 210 is disposedclose to the vehicle main body 10 side.

The front fork 21 includes an axle side unit 100 and a main body sideunit 200. The axle side unit 100 has the outer member 110, and isattached to the axle of the front wheel 2, and the main body side unit200 has the inner tube 210, and is attached to the vehicle main body 10.The front fork 21 includes a front wheel side spring 500 which isdisposed between the axle side unit 100 and the main body side unit 200such that the front wheel side spring 500 absorbs vibration which isapplied to the front wheel 2 due to roughness of a road surface.

The outer member 110 and the inner tube 210 are cylindrical memberswhich are coaxially disposed, and hereinafter, a direction (axialdirection) of a center line of this circular cylinder may be referred toas a “vertical direction”. In the embodiment, an “upper” side representsa region in which the vehicle main body 10 is disposed, and a “lower”side represents a region in which the front wheel 2 is disposed. Theaxle side unit 100 and the main body side unit 200 move relatively toeach other in the vertical direction (axial direction) such that thefront fork 21 absorbs and suppresses vibration induced by roughness of aroad surface while supporting the front wheel 2.

Configuration of Axle Side Unit 100

The axle side unit 100 includes the outer member 110 that is attached tothe axle of the front wheel 2; a damping force generation unit 130 thatgenerates a damping force using the viscous resistance of oil which isan example of the fluid; a rod 150 that holds the damping forcegeneration unit 130; and a rod holding member 160 that holds a lower endportion of the rod 150.

The axle side unit 100 includes a spherical ball 166 that is insertedinto an axial recess portion 161 a (which will be described later) ofthe rod holding member 160, and a restricting member 167 that restrictsa movement of the ball 166.

The axle side unit 100 includes a spring support member 170 thatsupports a lower end portion of the front wheel side spring 500; asupport-member holding member 180 that holds the spring support member170; and a guide member 190 that guides an axial movement of the innertube 210.

Configuration of Outer Member 110

The outer member 110 has a cylindrical portion 111 having a cylindricalshape into which the inner tube 210 is inserted, and an axle bracketportion 112 to which the axle of the front wheel 2 can be attached.

The cylindrical portion 111 has an oil seal 113 and a slide bush 114 inan upper end portion thereof. The oil seal 113 seals a gap between theouter circumferential surface of the inner tube 210 and the cylindricalportion 111, and the slide bush 114 helps the cylindrical portion tosmoothly slide against the outer circumferential surface of the innertube 210.

An axial through-hole 112 a and an axle mounting hole 112 b are formedin the axle bracket portion 112. The rod holding member 160 is insertedinto the axial through-hole 112 a in the axial direction, and the axleof the front wheel 2 can pass through in the direction which intersectswith the axial direction and be attached to the axle mounting hole 112b.

Configuration of Damping Force Generation Unit 130

The damping force generation unit 130 includes a piston 131 thatpartitions off a working oil chamber 50 which is formed in the internalspace of a cylinder 230 (which will be described later); an upper endside valve 136 that is provided at an upper end of the piston 131; and alower end side valve 137 that is provided on a lower end side of thepiston 131. The damping force generation unit 130 includes a piston bolt140 that supports the piston 131, the upper end side valve 136, thelower end side valve 137, and the like, and a nut 145 that positions thepiston 131, the upper end side valve 136, the lower end side valve 137,and the like by being tightened to the piston bolt 140.

The piston 131 is a cylindrical member, and a seal member for sealingthe gap between the cylinder 230 and the piston 131 is provided on theouter circumferential surface of the piston 131. The piston 131 isformed with a first through-hole 132 and a second through-hole 133 whichare axial through-holes. The piston 131 is formed with a first radialcommunication path 134 and a second radial communication path 135. Thefirst radial communication path 134 is formed in an upper end portion ofthe piston 131 in such a way as to extend in a radial direction, andcommunicates with the first through-hole 132. The second radialcommunication path 135 is formed in a lower end portion of the piston131 in such a way as to extend in the radial direction, and communicateswith the second through-hole 133. A plurality of (for example, three)the first through-holes 132 and a plurality of (for example, three) thesecond through-holes 133 are formed in a circumferential direction, andthe first radial communication path 134 and the second radialcommunication path 135 are positioned so as to correspond to the firstthrough-hole 132 and the second through-hole 133, respectively.

The upper end side valve 136 is configured with a single disk-shapedmetal plate or a plurality of disk-shaped metal plates which arestacked. A through-hole is formed at the center of each of the metalplates of the upper end side valve 136, and a shaft portion 141 (whichwill be described later) of the piston bolt 140 passes through thethrough-holes. The upper end side valve 136 blocks the secondthrough-hole 133, and opens the first through-hole 132.

The lower end side valve 137 is formed by stacking a plurality ofdisk-shaped metal plates. A through-hole is formed at the center of eachof the metal plates of the lower end side valve 137, and the shaftportion 141 (which will be described later) of the piston bolt 140passes through the through-holes. The lower end side valve 137 blocksthe first through-hole 132, and opens the second through-hole 133.

The piston bolt 140 has a columnar shaft portion 141 that is provided atan upper end of the piston bolt 140, and a columnar base portion 142that is provided on a lower end side of the piston bolt 140, and has aradius which is greater than the radius of the shaft portion 141. Thepiston bolt 140 is formed with a recess portion 143 that is recessedfrom a lower end surface of the base portion 142 toward the shaftportion 141. In addition, the base portion 142 of the piston bolt 140may have, for example, a shape of a hexagonal column or a shape of aprism.

An upper end portion of the shaft portion 141 is formed with a malescrew that is tightened to a female screw formed on the nut 145.

The inner circumferential surface of a lower end portion of the recessportion 143 is formed with a female screw that is tightened to a malescrew formed on an upper end portion of the rod 150. A radialthrough-hole 144 is radially formed in an upper end portion of therecess portion 143 so that the outer side of the shaft portion 141 cancommunicate with the recess portion 143.

An upper end portion of the nut 145 is formed with a female screw 146 towhich a male screw of the piston bolt 140 is tightened, and a columnarrecess portion 147 is recessed from a lower end surface of the nut 145,is formed below the female screw 146, and has a radius which is greaterthan the minor radius of the female screw 146. In addition, the nut 145is formed with an inclination direction through-hole 148. Theinclination direction through-hole 148 penetrates in the direction ofbeing inclined in the axial direction to communicate with the outerportion of the nut 145 and the recess portion 147. In addition, a platevalve 149 which covers an opening portion in the inclination directionthrough-hole 148 is provided on a lower end side of the nut 145.

The damping force generation unit 130 configured as described above isheld by the rod 150 by tightening the male screw formed on the upper endportion of the rod 150 to the female screw formed on the recess portion143 of the piston bolt 140. The piston 131 is in contact with the innercircumferential surface of the cylinder 230 via the seal member that isprovided on the outer circumferential surface of the piston 131, and thepiston 131 partitions off the internal space of the cylinder 230 into afirst oil chamber 51 (which is disposed above the piston 131) and asecond oil chamber 52 (which is disposed below the piston).

Configuration of Rod 150

The rod 150 is a cylindrical member, and male screws are respectivelyformed on the outer circumferential surfaces of the upper end portionand the lower end portions of the rod 150. The male screw formed on theupper end portion is tightened to the piston bolt 140 of the dampingforce generation unit 130, and the male screw formed on the lower endportion is tightened to a female screw 161 d that is formed on an upperend side columnar portion 161 of the rod holding member 160. A lock nut155 is tightened to the male screw that is formed on the lower endportion such that the rod 150 is fixed to the rod holding member 160.

A female screw may be formed on the inner circumferential surface of thelower end portion of the rod 150.

Configuration of Rod Holding Member 160

The rod holding member 160 has a plurality of columnar portions whichhave different diameters, and specifically, the rod holding member 160has the upper end side columnar portion 161 that is an upper endportion, a lower end side columnar portion 162 that is a lower endportion, and an intermediate columnar portion 163 that is disposedbetween the upper end side columnar portion 161 and the lower end sidecolumnar portion 162.

The upper end side columnar portion 161 is formed with the axial recessportion 161 a, a radial recess portion 161 b, and a radial through-hole161 c. The axial recess portion 161 a is axially recessed from the upperend surface of the upper end side columnar portion 161. The radialrecess portion 161 b is radially recessed from the outer circumferentialsurface of the upper end side columnar portion 161 across the entirecircumference thereof. The radial through-hole 161 c radially penetratesthe axial recess portion 161 a and the radial recess portion 161 b.

The axial recess portion 161 a is formed with the female screw 161 dthat is tightened to the male screw formed on the lower end portion ofthe rod 150. The axial recess portion 161 a is formed with an inclinedsurface 161 e which is inclined with respect to the axial direction suchthat the inner diameter of the axial recess portion 161 a decreasesgradually toward the lower side.

A lower end portion of the upper end side columnar portion 161 is formedwith a male screw 161 f that is tightened to a female screw 181 (whichwill be described later) which is formed on the support-member holdingmember 180.

The intermediate columnar portion 163 has a diameter that is smallerthan the inner diameter of the axial through-hole 112 a which is formedin the outer member 110, and the intermediate columnar portion 163 isfitted into the axial through-hole 112 a of the outer member 110.

A male screw 162 a is formed on the outer circumferential surface of thelower end side columnar portion 162.

The male screw 162 a formed on the lower end side columnar portion 162is tightened to a nut 165 which is inserted into the axial through-hole112 a of the outer member 110, and thus, the rod holding member 160 isfixed to the outer member 110.

Configuration of Restricting Member 167

The restricting member 167 is a stepped member which is formed in thecylindrical shape. A male screw is formed on the outer circumferentialsurface of an upper end portion of the restricting member 167. A femalescrew formed on the inner circumferential surface of the lower endportion of the rod 150 is tightened to this male screw such that therestricting member 167 is fixed to the rod 150. A lower end portion ofthe restricting member 167 restricts a movement of the ball 166 that isinserted into the axial recess portion 161 a of the rod holding member160.

Configuration of Spring Support Member 170

The spring support member 170 is a cylindrical member, and is fixed toan upper end portion of the support-member holding member 180. Fixing bywelding, press-fitting, or using a stopper ring can be used as a fixingmethod.

Configuration of Support-Member Holding Member 180

The support-member holding member 180 is a cylindrical member. The lowerend portion of the support-member holding member 180 is formed with thefemale screw 181 that is tightened to the male screw 161 f which isformed on the rod holding member 160. The male screw 161 f formed on therod holding member 160 is tightened to the female screw 181 such thatthe support-member holding member 180 is fixed to the rod holding member160. In addition, the support-member holding member 180 and the rodholding member 160 may be fixed by using the stopper ring.

A communication hole 182 is formed in the support-member holding member180 such that the inside and the outside of the support-member holdingmember 180 communicate with each other, and the communication hole 182is disposed at an axial position which correspond to the position of theradial recess portion 161 b of the rod holding member 160.

Configuration of Guide Member 190

The guide member 190 has a cylindrical portion 191 having a cylindricalshape, and an inward portion 192 that is formed to be radially orientedtoward the inner side from a lower end portion of the cylindricalportion 191.

The inward portion 192 is interposed between the rod holding member 160and the outer member 110 such that the guide member 190 is fixed betweenthe rod holding member 160 and the outer member 110.

A chamfer is formed in a lower end portion of the inward portion 192,and a seal member 195, such as an O-ring, is fitted into a space whichis formed between the chamfer and the rod holding member 160. The sealmember 195 seals the gap between the guide member 190, the rod holdingmember 160, and the outer member 110. Accordingly, the inner space ofthe cylindrical portion 111 of the outer member 110 is held in a liquidtight manner

In the axle side unit 100 configured as described above, a reservoirchamber 40 is formed between (i) the inner circumferential surface ofthe outer member 110 and (ii) the outer circumferential surfaces of therod 150 and the support-member holding member 180. The reservoir chamber40 stores oil that is sealed in the front fork 21.

Configuration of Main Body Side Unit 200

The main body side unit 200 includes the cylindrical inner tube 210,both ends of which are opened, and a cap 220 that is attached to anupper end portion of the inner tube 210.

The main body side unit 200 includes the cylinder 230 having acylindrical shape, and a seal member 240 that is attached to a lower endportion of the cylinder 230, and seals the inner space of the cylinder230.

The main body side unit 200 includes a front wheel side spring-lengthchanging unit 250 and the front wheel side flow path switching unit 300.The front wheel side spring-length changing unit 250 supports an upperend portion of the front wheel side spring 500, and adjusts (changes)the length of the front wheel side spring 500, and the front wheel sideflow path switching unit 300 is attached to an upper end portion of thecylinder 230, and switches a flow path of oil as an example of a fluid.

Configuration of Inner Tube 210

The inner tube 210 is a cylindrical member.

The inner tube 210 includes a cylindrical slide bush 211 which helps theinner tube 210 to smoothly slide against the inner circumferentialsurface of the cylindrical portion 111 of the outer member 110 in thelower end portion.

The upper end portion of the inner tube 210 is formed with a femalescrew 213 which is tightened to a male screw 221 (which will bedescribed later) that is formed on the cap 220.

Configuration of Cap 220

The cap 220 is a substantially cylindrical member. The outercircumferential surface of the cap 220 is formed with the male screw 221that is tightened to the female screw 213 which is formed on the innertube 210, and the inner circumferential surface of the cap 220 is formedwith a female screw which is tightened to male screw that is formed onthe front wheel side spring-length changing unit 250 or the front wheelside flow path switching unit 300. The cap 220 is attached to the innertube 210, and holds the front wheel side spring-length changing unit 250and the front wheel side flow path switching unit 300.

The cap 220 has a seal member 222, such as an O-ring, that holds theinner space of the inner tube 210 in a liquid tight manner

Configuration of Cylinder 230

The cylinder 230 is a cylindrical member. The outer circumferentialsurface of the upper end portion of the cylinder 230 is formed with afemale screw that is tightened to a male screw formed on the front wheelside flow path switching unit 300, and the inner circumferential surfaceof the lower end portion of the cylinder 230 is formed with a femalescrew that is tightened to a male screw which is formed on the sealmember 240.

Configuration of Seal Member 240

The seal member 240 is a cylindrical member. The outer circumferentialsurface of the seal member 240 is formed with a male screw that istightened to the female screw formed on the inner circumferentialsurface of the lower end portion of the cylinder 230. The female screwformed on the inner circumferential surface of the lower end portion ofthe cylinder 230 is tightened to this male screw such that the sealmember 240 is held by the cylinder 230.

The seal member 240 has a slide bush 245 on the inner circumference, andthe slide bush 245 helps the outer circumferential surface of the rod150 to smoothly slide against the seal member 240. The seal member 240has a seal member 246, such as an O-ring, that is disposed between theseal member 240 and the outer circumferential surface of the rod 150,and a seal member 247, such as an O-ring, that is disposed between theseal member 240 and the inner circumferential surface of the cylinder230, and as a result, the inner space of the cylinder 230 is held in aliquid tight manner.

A shock absorbing member 248 is attached to an upper end portion of theseal member 240, and absorbs shock that is applied when the dampingforce generation unit 130 comes into contact with the shock absorbingmember 248. The shock absorbing member 248 can be formed as an elasticmember made of resin or rubber.

Configuration of Front Wheel Side Spring-Length Changing Unit 250

The front wheel side spring-length changing unit 250 includes a basemember 260 and an upper end portion support member 270. The base member260 is fixed to the cap 220, and the upper end portion support member270 supports the upper end portion of the front wheel side spring 500,and changes the length of the front wheel side spring 500 by movingrelatively to the base member 260 in the axial direction.

The base member 260 is a substantially cylindrical member. A protrusionportion 260 a is formed in an upper end portion of the base member 260.The protrusion portion 260 a is fixed to the cap 220.

However, the upper end portion of the base member 260 is formed with aprotrusion portion 260 b of which a part in the circumferentialdirection protrudes in the radial direction. The upper end portion ofthe base member 260 forms a flow path 41 for discharging oil in thecylinder 230 to the reservoir chamber 40 between the inner surface ofthe protrusion portion 260 b and the outer circumferential surface of alower end portion of a support member 400 (which will be describedlater).

The base member 260 has a cylindrical slide bush 261 and a seal member262, such as an O-ring, in a lower end portion of the base member 260.The slide bush 261 is fitted to the outer circumference of the basemember 260, and helps the base member 260 to smoothly slide against theinner circumferential surface of the upper end portion support member270, and the O-ring is provided inside the slide bush 261. An annularflow path 61 is formed between the inner circumferential surface of thebase member 260 and the outer circumferential surface of the cylinder230.

The upper end portion support member 270 has a cylindrical portion 271having a cylindrical shape, and an inward portion 272 that is formed tobe radially oriented toward the inner side from a lower end portion ofthe cylindrical portion 271. The upper end portion support member 270forms a jack chamber 60 in a space between the outer circumferentialsurface of the cylinder 230 and the lower end portion of the base member260, and the jack chamber 60 accommodates oil used to change theposition of the upper end portion support member 270 with respect to thebase member 260.

The inner diameter of the cylindrical portion 271 is set to be smallerthan the outer diameter of the slide bush 261 that is fitted to the basemember 260. A radial through-hole 273 is radially formed in thecylindrical portion 271 so that the inside and the outside of thecylindrical portion 271 communicate with each other. Oil is dischargedfrom the jack chamber 60 to the reservoir chamber 40 via the radialthrough-hole 273 such that the amount of movement of the upper endportion support member 270 with respect to the base member 260 isrestricted.

A seal member 274, such as an O-ring, is provided on the innercircumference side of the inward portion 272, and holds the jack chamber60 in a liquid tight manner by sealing the gap between the inwardportion 272 and the outer circumferential surface of the cylinder 230.

Oil in the cylinder 230 is supplied to the jack chamber 60 via theannular flow path 61 that is formed between the inner circumferentialsurface of the base member 260 and the outer circumferential surface ofthe cylinder 230. A detailed description thereof will be given later.

Configuration of Front Wheel Side Flow Path Switching Unit 300

FIG. 3A is a view schematically illustrating an open and closed state ofthe flow path in a case where the front wheel side flow path switchingunit 300 is in a first switch state (which will be described later).FIG. 3B is a view schematically illustrating an open and closed state ofthe flow path in a case where the front wheel side flow path switchingunit 300 is in a second switch state (which will be described later).FIG. 3C is a view schematically illustrating an open and closed state ofthe flow path in case where the front wheel side flow path switchingunit 300 is in a third switch state (which will be described later).FIG. 3D is a view schematically illustrating an open and closed state ofthe flow path in case where the front wheel side flow path switchingunit 300 is in a fourth switch state (which will be described later).

The front wheel side flow path switching unit 300 is a device whichswitches supply of oil discharged by a pump 600 (which will be describedlater) to the reservoir chamber 40, supply of oil discharged by the pump600 to the jack chamber 60, or supply of oil accommodated in the jackchamber 60 to the reservoir chamber 40.

The front wheel side flow path switching unit 300 is formed with a firstcommunication path R1 which communicates with the inside of the cylinder230 and the reservoir chamber 40, a second communication path R2 whichcommunicates with the inside of the cylinder 230 and the jack chamber60, and a third communication path R3 and a fourth communication path R4which communicate with the jack chamber 60 and the reservoir chamber 40.

In addition, the front wheel side flow path switching unit 300 includesa first on-off valve 301 which opens and closes the first communicationpath R1, a second on-off valve 302 which opens and closes the secondcommunication path R2, a third on-off valve 303 which opens and closesthe third communication path R3, and a fourth on-off valve 304 whichopens and closes the fourth communication path R4.

In a case where the front wheel side flow path switching unit 300 is inthe first switch state, as illustrated in FIG. 3A, the first on-offvalve 301 is open and the third on-off valve 303 and the fourth on-offvalve 304 are closed, and thus, the oil discharged by the pump 600reaches the reservoir chamber 40 via the first communication path R1. Inthis case, since the pressure of the oil discharged by the pump 600 isnot as high as the second on-off valve 302 is opened, the oil does notcirculate in the second communication path R2. In other words, since thefirst on-off valve 301 is open, the second on-off valve 302 is closed.In addition, in the first switch state, an amount of oil in the jackchamber 60 neither increases nor decreases.

In a case where the front wheel side flow path switching unit 300 is inthe second switch state, as illustrated in FIG. 3B, the first on-offvalve 301, the third on-off valve 303, the fourth on-off valve 304 areclosed, and thus, the oil discharged by the pump 600 opens the secondon-off valve 302 and reaches the jack chamber 60 via the secondcommunication path R2. In the second switch state, the amount of oil inthe jack chamber 60 increases. Therefore, the jack chamber 60 extends.

In a case where the front wheel side flow path switching unit 300 is inthe third switch state, as illustrated in FIG. 3C, the first on-offvalve 301 and the fourth on-off valve 304 are closed, the third on-offvalve 303 is open, and thus, the oil in the jack chamber 60 reaches thereservoir chamber 40 via the third communication path R3. In the thirdswitch state, an amount of oil in the jack chamber 60 decreases.Therefore, the jack chamber 60 contracts.

In a case where the front wheel side flow path switching unit 300 is inthe fourth switch state, as illustrated in FIG. 3D, the first on-offvalve 301 and the third on-off valve 303 are closed, the fourth on-offvalve 304 is open, and thus, the oil in the jack chamber 60 reaches thereservoir chamber 40 via the fourth communication path R4. As will bedescribed later, a flow path area of the fourth communication path R4 iswider than a flow path area of the third communication path R3, in thefourth switch state, an amount of oil in the jack chamber 60 decreasesfaster than that of the third switch state. Therefore, the jack chamber60 rapidly contracts.

Specific Configuration of Front Wheel Side Flow Path Switching Unit 300

FIG. 4 is an enlarged view of a portion IV in FIG. 2.

FIG. 5 is an enlarged view of a portion V in FIG. 4.

The front wheel side flow path switching unit 300 includes a first coilspring 311 which gives a force in the direction in which the firstcommunication path R1 is closed with respect to the first on-off valve301, a second coil spring 312 which gives a force in the direction inwhich the second communication path R2 is closed with respect to thesecond on-off valve 302, and a third coil spring 313 which gives a forcein the direction in which the third communication path R3 is closed withrespect to the third on-off valve 303.

In addition, the front wheel side flow path switching unit 300 includesa control valve 305 which controls opening and closing of the firston-off valve 301, a control valve coil spring 315 which is providedbelow the control valve 305, and a front wheel side solenoid 320 whichmoves the control valve 305 downward against a spring force of thecontrol valve coil spring 315.

In addition, the front wheel side flow path switching unit 300 includesa push rod 316 which moves the third on-off valve 303 downward against aspring force of the third coil spring 313 provided below the thirdon-off valve 303. The push rod 316 moves downward being pushed by thecontrol valve 305.

In addition, the front wheel side flow path switching unit 300 includesa unit main body 330 and a second on-off valve support member 370 whichis mounted on the unit main body 330 and supports the second on-offvalve 302. In addition, the front wheel side flow path switching unit300 includes a fourth on-off valve support member 380 which supports thefourth on-off valve 304, and a cover member 395 which covers an openingportion of the fourth on-off valve support member 380. In addition, thefront wheel side flow path switching unit 300 includes a coil springsupport member 388 and a leaf spring 389 which are disposed between thesecond on-off valve support member 370 and an inward portion 382 (whichwill be described later) of the fourth on-off valve support member 380,and support an upper end portion of the second coil spring 312.

Regarding First On-Off Valve 301

The first on-off valve 301 includes a cylindrical portion 301 a having acylindrical shape and a conical portion 301 b having a conical shape andhaving an inclined surface 301 c which is inclined with respect to theaxial direction such that the outer diameter thereof gradually decreasestoward the lower side.

A seal member 306, such as an O-ring, is fitted to a space between anouter circumferential surface 301 d of the cylindrical portion 301 a andan upper end side columnar portion 340 (which will be described later)of the unit main body 330.

A through-hole 301 e in the axial direction is formed in a centerportion of the conical portion 301 b. The through-hole 301 ecommunicates with the inner portion of the cylindrical portion 301 a andthe outer portion of the conical portion 301 b. The through-hole 301 ecommunicates with an axial communication hole 351 (which will bedescribed later) of the unit main body 330, and a space (hereinafter,referred to as “first on-off valve back pressure chamber B1”) in whichthe oil that gives a downward force with respect to the first on-offvalve 301 exists. In addition, the first on-off valve back pressurechamber B1 is a space surrounded by a lower end surface of a case 325 ofthe front wheel side solenoid 320 which will be described later, aspring support member 307, a center protrusion 347 of the unit main body330, or the like.

The first coil spring 311 is disposed on an inner side of thecylindrical portion 301 a of the first on-off valve 301, and the lowerend portion is supported on an upper end surface of the conical portion301 b of the first on-off valve 301.

The front wheel side flow path switching unit 300 includes a springsupport member 307 which supports an upper end portion of the first coilspring 311, and a retaining ring 308 which suppresses upward movement ofthe seal member 306.

The retaining ring 308 has a cylindrical shape, and an inner diameterthereof is greater than an outer diameter of the cylindrical portion 301a of the first on-off valve 301. An outer diameter of the retaining ring308 is greater than an inner diameter of a first columnar recess portion346 a of the upper end side columnar portion 340 (which will bedescribed later) of the unit main body 330, and is pressurized to thefirst columnar recess portion 346 a. In addition, the retaining ring 308suppresses the upward movement of the seal member 306. In addition, theretaining ring 308 may be formed to be integrated with the upper endside columnar portion 340.

The spring support member 307 is a doughnut-shaped thin plate a centerportion of which is formed with a through-hole having a diameter that isgreater than an outer diameter of the center protrusion 347 (which willbe described later) of the unit main body 330. The spring support member307 is disposed above the first on-off valve 301, the first coil spring311, the seal member 306, and the retaining ring 308, and suppressesupward movement of the first on-off valve 301 and the first coil spring311.

Configuration of Fourth On-Off Valve 304

The fourth on-off valve 304 includes a first columnar portion 391 and asecond columnar portion 392 which have columnar shapes and which havedifferent diameters from each other. A diameter of the first columnarportion 391 is smaller than a diameter of the second columnar portion392.

In addition, an axial through-hole 393 which penetrates in the axialdirection is formed in the fourth on-off valve 304. The axialthrough-hole 393 includes a first through-hole 393 a and a secondthrough-hole 393 b which have a columnar shape and have differentdiameters from each other. A hole diameter d1 of the first through-hole393 a is greater than a hole diameter d2 of the second through-hole 393b. The hole diameter d2 of the second through-hole 393 b is greater thana diameter of a second shaft portion 318 (which will be described later)of the push rod 316, and the hole diameter d1 of the first through-hole393 a is greater than a diameter of a third shaft portion 319 (whichwill be described later) of the push rod 316 such that the push rod 316passes through the inside of the axial through-hole 393. However, inorder to suppress the downward movement of the push rod 316, the holediameter d2 of the second through-hole 393 b is greater than thediameter of the third shaft portion 319 of the push rod 316.

The second columnar portion 392 is formed with a lower end side recessportion 392 a which is recessed from the lower end surface. In anopening portion of the second through-hole 393 b in the lower end siderecess portion 392 a, a recess portion which is along a shape of theupper end portion of the spherical third on-off valve 303 is formed.

Configuration of Control Valve 305

The control valve 305 is a columnar member. A groove 305 a which isrecessed across the entire circumference thereof is formed on an outercircumferential surface of the control valve 305. In addition, thecontrol valve 305 is formed with an upper end side recess portion 305 band an inclined hole 305 c. The upper end side recess portion 305 b isrecessed from the upper end surface in the axial direction. The inclinedhole 305 c is inclined with respect to the axial direction tocommunicate with the upper end side recess portion 305 b and a lowerpart of the control valve 305.

The control valve 305 moves downward against a spring force of thecontrol valve coil spring 315 by being pressed downward by an operationrod 324 of the front wheel side solenoid 320 inserted into the upper endside recess portion 305 b. Meanwhile, in a case where the operation rod324 moves upward, the control valve 305 moves upward by the spring forceof the control valve coil spring 315.

Configuration of Push Rod 316

As illustrated in FIG. 4, the push rod 316 includes a columnar firstshaft portion 317 which is positioned on the upper end portion side, thecolumnar second shaft portion 318 which is positioned on the lower endportion side, and the columnar third shaft portion 319 which ispositioned between the first shaft portion 317 and the second shaftportion 318. The diameter of the third shaft portion 319 is greater thanthe diameters of the first shaft portion 317 and the second shaftportion 318. In addition, the third on-off valve 303 and the push rod316 may be integrated with each other.

Configuration of Front Wheel Side Solenoid 320

The front wheel side solenoid 320 is a proportional solenoid including acoil 321, a core 322 which is disposed on an inner side of the coil 321,a plunger 323 which is guided into the core 322, and the operation rod324 which is linked to the plunger 323.

In addition, the front wheel side solenoid 320 includes the case 325which accommodates the coil 321, the core 322, the plunger 323 and thelike, and a cover 326 which covers an opening portion of the case 325.

The operation rod 324 is hollow, an upper end portion thereof isaccommodated on the inside of the case 325, and a lower end portionthereof protrudes from the case 325.

The case 325 includes a cylindrical portion 325 a having a cylindricalshape and an inward portion 325 b which is formed to be oriented towardthe inner side in the radial direction from the lower end portion in thecylindrical portion 325 a. The inward portion 325 b is formed with athrough-hole which passes through the operation rod 324. A guide bush325 c which guides the movement of the operation rod 324 is fitted tothe inward portion 325 b.

A front wheel side solenoid 320 configured as described above isenergized to the coil 321 via a connector mounted on the cap 220 and alead line, and an axial thrust force is generated in the plunger 323 inaccordance with an energization current. In addition, the operation rod324 which is linked to the plunger 323 moves in the axial direction bythe thrust force of the plunger 323. In the front wheel side solenoid320 according to the embodiment, the axial thrust force is generated inthe plunger 323 such that an amount of protrusion of the operation rod324 from the case 325 increases as the energization current to the coil321 increases.

In addition, an energization amount to the coil 321 is controlled by thecontrol device 70.

Configuration of Unit Main Body 330

The unit main body 330 includes the columnar upper end side columnarportion 340 which is provided on the upper end side, and a firstcylindrical portion 350 and a second cylindrical portion 360 which areprovided below the upper end side columnar portion 340, have cylindricalshapes and have different outer diameters from each other.

An outer diameter of the upper end side columnar portion 340 issubstantially the same as an outer diameter of the first cylindricalportion 350, and an outer diameter of the first cylindrical portion 350is greater than an outer diameter of the second cylindrical portion 360.

An upper end side center recess portion 342, a lower end side centerrecess portion 344, a center communication hole 345 are formed in acenter portion of the upper end side columnar portion 340. The upper endside center recess portion 342 is recessed downward from an upper endsurface 341. The lower end side center recess portion 344 is recessed inthe upward direction from a lower end surface 343. The centercommunication hole 345 communicates with the upper end side centerrecess portion 342 and the lower end side center recess portion 344.

FIG. 6 is a perspective view of the upper end side columnar portion 340of a unit main body 330.

The upper end side center recess portion 342 includes an accommodationportion 342 a which accommodates the control valve 305 to be movable. Inaddition, the upper end side center recess portion 342 includes a siderecess portion 342 b which is recessed in the axial direction from anupper end surface of the center protrusion 347 (which will be describedlater) further to a part below a lower limit of a moving range of thecontrol valve 305 so as to be continuous to the accommodation portion342 a in the radial direction which intersects with the axial direction.

In the upper end side columnar portion 340, an upper end sideintermediate recess portion 346 is formed between the upper end sidecenter recess portion 342 and the outer circumferential surface. Theupper end side intermediate recess portion 346 is recessed downward fromthe upper end surface 341. The upper end side intermediate recessportion 346 includes three columnar recess portions including a firstcolumnar recess portion 346 a, a second columnar recess portion 346 b,and a third columnar recess portion 346 c which have columnar shapes andhave different diameters from each other. In addition, the upper endside columnar portion 340 is formed with an intersecting-directioncommunication hole 346 d which is a hole that communicates with thesecond columnar recess portion 346 b and the outer portion in thedirection which intersects with the axial direction.

In addition, in the center portion of the upper end side columnarportion 340, the center protrusion 347 which protrudes upward from theupper end surface 341 is provided around the upper end side centerrecess portion 342.

In addition, the upper end side columnar portion 340 includes a flangeportion 348 which is oriented toward the outer side in the radialdirection from the upper end portion. The flange portion 348 is formedwith a cut-out portion 348 a of which a part in the circumferentialdirection is cut out.

In addition, the upper end side columnar portion 340 is formed with afirst radial communication hole 349 a and a second radial communicationhole 349 b. The first radial communication hole 349 a is a through-holein the radial direction that communicates with the upper end side centerrecess portion 342 and the cut-out portion 348 a. The second radialcommunication hole 349 b is a through-hole in the radial direction thatcommunicates with the lower end side center recess portion 344 and theouter portion.

One first radial communication hole 349 a is formed at a position atwhich the side recess portion 342 b of the upper end side center recessportion 342 is not formed, in the circumferential direction. In theembodiment, as illustrated in FIG. 6, the first radial communicationhole 349 a and the side recess portion 342 b are formed on sidesopposite to each other across a center line. The first radialcommunication hole 349 a is a columnar hole, and an example in which ahole diameter thereof is the same as that of the groove 305 a of thecontrol valve 305 in the axial direction can be employed.

One or a plurality of the second radial communication holes 349 b areformed at a part at which the upper end side intermediate recess portion346 is not formed in the circumferential direction.

The axial communication hole 351 is formed in the first cylindricalportion 350. The axial communication hole 351 is a through-hole in theaxial direction that communicates with (i) a space that is below thefirst cylindrical portion 350 and that is formed between the outercircumferential surface of the second cylindrical portion 360 and theinner circumferential surface of the cylinder 230 and (ii) the upper endside intermediate recess portion 346. One or a plurality of the axialcommunication holes 351 are formed in the circumferential direction.

A first radial recess portion 352, a second radial recess portion 353,and a male screw 354 are formed on the outer circumferential surface ofthe first cylindrical portion 350. The first radial recess portion 352and the second radial recess portion 353 are recessed in the radialdirection across the entire circumference thereof. The male screw 354 istightened to a female screw formed in the upper end portion of thecylinder 230.

A seal member 355, such as an O-ring, which seals a gap between thefirst radial recess portion 352 and the base member 260 of the frontwheel side spring-length changing unit 250 is fitted to the first radialrecess portion 352.

A seal member 356, such as an O-ring, which seals a gap between thesecond radial recess portion 353 and the cylinder 230, is fitted to thesecond radial recess portion 353.

In addition, the first cylindrical portion 350 is formed with a thirdradial communication hole 357 which is a through-hole in the radialdirection that communicates with the inner portion and the outerportion. A position in the radial direction of the third radialcommunication hole 357 is between the first radial recess portion 352and the second radial recess portion 353.

A female screw 361 is formed in the lower end portion of the innercircumferential surface of the second cylindrical portion 360. A malescrew 373 a (which will be described later) formed on the outercircumferential surface of the second on-off valve support member 370 istightened to the female screw 361.

Configuration of Second On-Off Valve Support Member 370

The second on-off valve support member 370 includes an upper end sidecylindrical portion 371 which has a cylindrical shape and is positionedon the upper end portion side, a columnar portion 372 which ispositioned in the center portion, and a lower end side cylindricalportion 373 which is positioned on the lower end portion side.

An outer diameter of the upper end side cylindrical portion 371 issmaller than the diameter of the inner circumferential surface of thefirst cylindrical portion 350 of the unit main body 330, and the upperend side cylindrical portion 371 is inserted into the first cylindricalportion 350 of the unit main body 330.

The columnar portion 372 is formed with a plurality of (three in theembodiment) axial through-holes 372 a which penetrate in the axialdirection at an equivalent interval in the circumferential directionaround the center line. The opening portion on the upper end side ineach of the axial through-holes 372 a is formed with a recess portionwhich is along the shape of the lower end portion of the sphericalsecond on-off valve 302. A groove 372 b is formed on the outercircumferential surface of the columnar portion 372 across the entirecircumference thereof. A seal member 374, such as an O-ring, which sealsa gap between the groove 372 b and the unit main body 330 is fitted tothe groove 372 b.

An inner circumferential surface of the lower end side cylindricalportion 373 is positioned on an outer side, in the radial direction, ofthe axial through-hole 372 a formed in the columnar portion 372. Themale screw 373 a is formed on an outer circumferential surface of thelower end side cylindrical portion 373. The male screw 373 a istightened to the female screw formed in the lower end portion of theunit main body 330. A collecting member 375 is provided on an inner sideof the lower end side cylindrical portion 373. The collecting member 375collects dust of oil discharged by the pump 600 (which will be describedlater).

The second on-off valve support member 370 is mounted on the unit mainbody 330 as the male screw 373 a formed on the outer circumferentialsurface of the lower end side cylindrical portion 373 is tightened tothe female screw 361 formed in the unit main body 330. In addition, onthe inner side of the upper end side cylindrical portion 371, threesecond on-off valves 302 which are disposed at an equivalent interval inthe circumferential direction, and a second on-off valve pressing member378 which presses the second coil spring 312 and three second on-offvalves 302, are accommodated. The second on-off valve 302 blocks theaxial through-hole 372 a by seating in the opening portion on the upperend side in the axial through-hole 372 a formed in the columnar portion372.

Configuration of Collecting Member 375

The collecting member 375 includes a disk-shaped net 376 and acylindrical holding member 377 which has a cylindrical shape and holdsthe net 376 on the inside thereof. The collecting member 375 is mountedon the lower end side cylindrical portion 373 as the holding member 377is pressurized to the lower end side cylindrical portion 373. Inaddition, the collecting member 375 may be configured only of the net376 that is directly attached to the lower end side cylindrical portion373 of the second on-off valve support member 370, for example, by anadhesive. In addition, the collecting member 375 and the lower end sidecylindrical portion 373 may be fixed by using the stopper ring.

Configuration of Second On-Off Valve Pressing Member 378

The second on-off valve pressing member 378 includes two cylindricalportions including a first cylindrical portion 378 a and a secondcylindrical portion 378 b which have cylindrical shapes and have thesame inner diameter and different outer diameters from each other. Aninner diameter of the second on-off valve pressing member 378 isslightly greater than an outer diameter of a columnar portion 383 of thefourth on-off valve support member 380. The second on-off valve pressingmember 378 moves in the axial direction while being supported by thecolumnar portion 383 of the fourth on-off valve support member 380.

An outer diameter of the first cylindrical portion 378 a is smaller thanan inner diameter of the second coil spring 312.

An outer diameter of the second cylindrical portion 378 b is greaterthan the inner diameter of the second coil spring 312, and is smallerthan an inner diameter of the upper end side cylindrical portion 371 ofthe second on-off valve support member 370. The second cylindricalportion 378 b supports the lower end portion of the second coil spring312 on the upper end surface.

A downward biasing force from the second coil spring 312 is applied tothe second on-off valve pressing member 378, and the second on-off valvepressing member 378 is positioned at a position at which the lower endsurface of the second cylindrical portion 378 b comes into contact withthree second on-off valves 302.

Configuration of Fourth On-Off Valve Support Member 380

The fourth on-off valve support member 380 includes a cylindricalportion 381 having a cylindrical shape, an inward portion 382 which isformed to be oriented toward the inner side in the radial direction fromthe lower end portion in the cylindrical portion 381, and a columnarportion 383 which is oriented downward from the lower end portion in theinward portion 382.

The fourth on-off valve support member 380 is formed with an axialthrough-hole 384 which penetrates the inward portion 382 and thecolumnar portion 383 in the axial direction. An inner portion of thecylindrical portion 381 and a part below the columnar portion 383communicate with each other via the axial through-hole 384.

The fourth on-off valve support member 380 is formed with a radialcommunication hole 385 which is a through-hole in the radial directionthat communicates with the cylindrical portion 381 and an outer side ofthe fourth on-off valve support member 380. A plurality of radialcommunication holes 385 are formed at an equivalent interval in thecircumferential direction.

In the inward portion 382, a protrusion 382 a which protrudes to anupper part in the axial direction from the upper end surface isprovided. An opening portion of the axial through-hole 384 in theprotrusion 382 a is formed with a recess portion which is along theshape of the lower end portion of the third on-off valve 303.

In the cylindrical portion 381 of the fourth on-off valve support member380, the fourth on-off valve 304, the third on-off valve 303, the thirdcoil spring 313, a support member 386 which supports the upper endportion of the third coil spring 313, and a suppressing member 387 whichsuppresses the movement of the third on-off valve 303 in the radialdirection, are accommodated.

The support member 386 is a doughnut-shaped thin plate a center portionof which is formed with a through-hole having a diameter that is smallerthan a diameter of the third on-off valve 303. The support member 386supports the upper end portion of the third coil spring 313 as aperiphery of the through-hole of the center portion comes into contactwith the upper end portion of the third coil spring 313. The downwardmovement of the third on-off valve 303 is suppressed by being fitted tothe through-hole of the center portion of the support member 386. At aposition at which a force which is generated to the support member 386and moves the third on-off valve 303 downward and an upward force givenfrom the third coil spring 313 are balanced, a position of the supportmember 386 is determined. In the embodiment, in a case where the thirdon-off valve 303 is not pressed from the push rod 316, the spring forceof the third coil spring 313 is set such that the third on-off valve 303blocks the opening portion of the second through-hole 393 b of thefourth on-off valve 304. Meanwhile, in a case where the third on-offvalve 303 is strongly pressed from the push rod 316, the spring force ofthe third coil spring 313 is set such that the third on-off valve 303 ismounted on the protrusion 382 a of the inward portion 382 of the fourthon-off valve support member 380, and blocks the opening portion on theupper side of the axial through-hole 384 formed in the fourth on-offvalve support member 380.

The suppressing member 387 is a doughnut-shaped thin plate a centerportion of which is formed with a center through-hole 387 a having adiameter that is greater than the diameter of the third on-off valve 303in the center portion. As the third on-off valve 303 is disposed on aninner side of the center through-hole 387 a of the suppressing member387, the movement of the third on-off valve 303 in the radial directionis suppressed. In addition, a plurality of periphery through-holes 387 bare formed at an equivalent interval in the circumferential direction onthe periphery of the center through-hole 387 a in the suppressing member387, and the oil circulates in the axial direction via the plurality ofthrough-holes.

Configuration of Cover Member 395

The cover member 395 includes three cylindrical portions including afirst cylindrical portion 396, a second cylindrical portion 397, and athird cylindrical portion 398 which have cylindrical shapes and have thesame inner diameters and different outer diameters from each other.

The outer diameter of the first cylindrical portion 396 is smaller thanthe diameter of the inner circumferential surface of the firstcylindrical portion 350 of the unit main body 330, and is greater thanthe inner diameter of the cylindrical portion 381 of the fourth on-offvalve support member 380. As the upper end surface of the cylindricalportion 381 of the fourth on-off valve support member 380 abuts againstthe lower end surface of the first cylindrical portion 396, the upwardmovement of the fourth on-off valve support member 380 is suppressed. Inaddition, a groove 396 a is formed on the outer circumferential surfaceof the first cylindrical portion 396. The groove 396 a is recessedacross the entire circumference of the outer circumferential surface ofthe first cylindrical portion 396. A seal member 399, such as an O-ring,which seals a gap between the groove 396 a and the unit main body 330 isfitted to the groove 396 a. In addition, the cover member 395 may beformed to be integrated with the unit main body 330.

The outer diameter of the second cylindrical portion 397 issubstantially the same as the inner diameter of the cylindrical portion381 of the fourth on-off valve support member 380. The secondcylindrical portion 397 is fitted to the inner side of the cylindricalportion 381 of the fourth on-off valve support member 380.

The outer diameter of the third cylindrical portion 398 is smaller thanthe inner diameter of the cylindrical portion 381 of the fourth on-offvalve support member 380. A seal member 314 which is an elastic member,such as a doughnut-shaped resin or rubber is pressurized to a spacebetween the third cylindrical portion 398 and the cylindrical portion381 of the fourth on-off valve support member 380. By reducing size ofthe third cylindrical portion 398 in the axial direction to be smallerthan the size of the seal member 314, and by bringing the fourth on-offvalve 304 into contact with the seal member 314, the flow path betweenthe fourth on-off valve 304 and the seal member 314 is sealed.

The inner diameter of the cover member 395 is greater than the diameterof the third shaft portion 319 of the push rod 316, and the push rod 316is disposed on the inner side of the cover member 395.

Configuration of Coil Spring Support Member 388

The coil spring support member 388 is a cross-shaped thin plate a centerportion of which is formed with a through-hole having a diameter whichis greater than the outer diameter of the columnar portion 383 of thefourth on-off valve support member 380. The thin plate has a cross shapewhen viewed in the axial direction. The coil spring support member 388supports the upper end portion of the second coil spring 312 on thelower end surface.

The size in the radial direction from the center of the through-hole inthe coil spring support member 388 is greater than a radius of the innercircumferential surface of the upper end side cylindrical portion 371 ofthe second on-off valve support member 370.

As the coil spring support member 388 abuts against the upper endsurface of the upper end side cylindrical portion 371 of the secondon-off valve support member 370, the downward movement thereof issuppressed.

The coil spring support member 388 is positioned at a position at whichthe downward biasing force applied from the leaf spring 389 and theupward biasing force applied from the second coil spring 312 arebalanced.

Configuration of Support Member 400

As illustrated in FIG. 4, the support member 400 has a cylindricalportion 401 having a cylindrical shape, and an inward portion 402 thatis formed to be radially oriented toward the inner side from a lower endportion of the cylindrical portion 401.

The outer circumferential surface of an upper end portion of thecylindrical portion 401 is formed with a male screw 403 that istightened to a female screw formed on the cap 220. The male screw 403formed on the outer circumferential surface of the cylindrical portion401 is tightened to the female screw formed on the cap 220 such that thesupport member 400 is held by the cap 220. The flange portion of thefourth on-off valve support member 380 and the flange portion of theunit main body 330 are interposed between the inward portion 402 and thefront wheel side solenoid 320 such that the support member 400 holds thefourth on-off valve support member 380 and the unit main body 330.

Regarding Positional Relationship Between Side Recess Portion 342 b andFirst Radial Communication Hole 349 a which are Formed in Upper End SideColumnar Portion 340 of Unit Main Body 330

FIGS. 7A and 7B are sectional views on a surface which is perpendicularin the axial direction and passes through the hole center of the firstradial communication hole 349 a of the upper end side columnar portion340 of the unit main body 330. FIG. 7A is a view illustrating a statewhere a position of the groove 305 a of the control valve 305 in theaxial direction and a position of the first radial communication hole349 a overlap each other. FIG. 7B is a view illustrating a state wherethe position of the groove 305 a of the control valve 305 in the axialdirection and the position of the first radial communication hole 349 ado not overlap each other.

In the front wheel side flow path switching unit 300 configured asdescribed above, in a case where the energization to the coil 321 of thefront wheel side solenoid 320 is stopped or a current which is less thana first reference current set in advance is supplied, the amount ofprotrusion of the operation rod 324 which protrudes from the case 325becomes less than a first reference amount set in advance. In theembodiment, in a case where the amount of protrusion of the operationrod 324 is less than the first reference amount, the position in theaxial direction of the groove 305 a of the control valve 305 overlapsthe first radial communication hole 349 a formed in the upper end sidecolumnar portion 340 of the unit main body 330. For example, in a casewhere the energization to the coil 321 of the front wheel side solenoid320 is stopped and the amount of protrusion of the operation rod 324 isan initial amount, the control valve 305 is positioned at an initialposition. In a case where the control valve 305 is at the initialposition, the center position in the axial direction of the groove 305 aof the control valve 305 and the position of the hole center of thefirst radial communication hole 349 a become the same as each other, andthe groove 305 a and the first radial communication hole 349 a overlapeach other. In addition, at this time, as illustrated in FIG. 7A, theside recess portion 342 b and the first radial communication hole 349 awhich are formed in the upper end side columnar portion 340 of the unitmain body 330 communicate with each other via the groove 305 a of thecontrol valve 305 and the first on-off valve back pressure chamber B1and the reservoir chamber 40 communicate with each other via the groove305 a of the control valve 305.

In a case where the current which is equal to or greater than the firstreference current is supplied to the coil 321 of the front wheel sidesolenoid 320, the amount of protrusion of the operation rod 324 from thecase 325 becomes equal to or greater than the first reference amount. Ina case where the amount of protrusion of the operation rod 324 is equalto or greater than the first reference amount, the control valve 305 ispushed down by the operation rod 324 such that the position in the axialdirection of the groove 305 a of the control valve 305 becomes aposition below the first radial communication hole 349 a formed in theupper end side columnar portion 340 of the unit main body 330. In otherwords, in a case where the amount of protrusion from the case 325 isequal to or greater than the first reference amount, the operation rod324 pushes down the control valve 305 until the position in the axialdirection of the groove 305 a of the control valve 305 is positionedbelow the first radial communication hole 349 a formed in the upper endside columnar portion 340 of the unit main body 330. In a case where thegroove 305 a of the control valve 305 is positioned below the firstradial communication hole 349 a, the position in the axial direction ofthe groove 305 a of the control valve 305 do not overlap the position ofthe first radial communication hole 349 a. In addition, at this time, asillustrated in FIG. 7B, the side recess portion 342 b and the firstradial communication hole 349 a which are formed in the upper end sidecolumnar portion 340 of the unit main body 330 do not communicate witheach other via the groove 305 a of the control valve 305, and the firston-off valve back pressure chamber B1 and the reservoir chamber 40 donot communicate with each other via the groove 305 a of the controlvalve 305.

In addition, an example in which the first reference amount of theamount of protrusion from the case 325 is half of a hole diameter of thefirst radial communication hole 349 a formed in the upper end sidecolumnar portion 340 of the unit main body 330 can be employed.

In a case where the current which is equal to or greater than a secondreference current set in advance to be a value that is greater than thefirst reference current is supplied to the coil 321 of the front wheelside solenoid 320, the operation rod 324 moves further downward, and theamount of protrusion of the operation rod 324 from the case 325 becomesequal to or greater than a second reference amount set in advance to bea value that is greater than the first reference amount. In a case wherethe amount of protrusion of the operation rod 324 is equal to or greaterthan the second reference amount, the control valve 305 comes intocontact with the push rod 316 and comes into contact with the thirdon-off valve 303, and the push rod 316 is placed in a state of beinginterposed between the control valve 305 and the third on-off valve 303.

In a case where the current which is equal to or greater than a thirdreference current set in advance to be a value that is greater than thesecond reference current is supplied to the coil 321 of the front wheelside solenoid 320, the amount of protrusion of the operation rod 324from the case 325 becomes equal to or greater than a third referenceamount set in advance to be a value that is greater than the secondreference amount. When the amount of protrusion of the operation rod 324from the case 325 becomes greater than the second reference amount, thepush rod 316 is pushed downward via the control valve 305. The push rod316 which has moved downward pushes down the third on-off valve 303, andthe third on-off valve 303 is separated from the opening portion of thesecond through-hole 393 b of the fourth on-off valve 304. In otherwords, the push rod 316 is pushed by the control valve 305 in a casewhere the amount of protrusion of the operation rod 324 from the case325 is greater than the second reference amount, the third on-off valve303 is pushed such that the third on-off valve 303 is separated from theopening portion of the second through-hole 393 b of the fourth on-offvalve 304. The third reference amount will be described later.

In a case where the current which is equal to or greater than a fourthreference current set in advance to be a value that is greater than thethird reference current is supplied to the coil 321 of the front wheelside solenoid 320, the amount of protrusion of the operation rod 324from the case 325 becomes equal to or greater than a fourth referenceamount set in advance to be a value that is greater than the thirdreference amount. In a case where the amount of protrusion of theoperation rod 324 is equal to or greater than the fourth referenceamount, the third on-off valve 303 which is pushed down by the push rod316 is mounted on the protrusion 382 a of the inward portion 382 of thefourth on-off valve support member 380, and blocks the opening portionon the upper side of the axial through-hole 384. In other words, in acase where the amount of protrusion of the operation rod 324 from thecase 325 is equal to or greater than the fourth reference amount, thepush rod 316 pushes the third on-off valve 303 to block the openingportion on the upper side of the axial through-hole 384 formed in thefourth on-off valve support member 380.

Hereinafter, a state where the energization to the coil 321 is stoppedor the current which is less than the first reference current issupplied, the position in the axial direction of the groove 305 a of thecontrol valve 305 overlaps the first radial communication hole 349 aformed in the upper end side columnar portion 340 of the unit main body330, and the first on-off valve back pressure chamber B1 and thereservoir chamber 40 communicate with each other via the groove 305 a ofthe control valve 305, is referred to as a first switch state.

In addition, a state where the current which is equal to or greater thanthe first reference current and is equal to or lower than the secondreference current is supplied to the coil 321, the operation rod 324pushes down the control valve 305 to the position at which the groove305 a of the control valve 305 does not overlap the first radialcommunication hole 349 a of the unit main body 330, the first on-offvalve back pressure chamber B1 and the reservoir chamber 40 do notcommunicate with each other via the groove 305 a of the control valve305, and the third on-off valve 303 blocks the opening portion of thesecond through-hole 393 b of the fourth on-off valve 304, is referred toas a second switch state.

In addition, a state where the current which is greater than the secondreference current is supplied to the coil 321, the first on-off valveback pressure chamber B1 and the reservoir chamber 40 do not communicatewith each other via the groove 305 a of the control valve 305, and thethird on-off valve 303 does not block both of the opening portion of thesecond through-hole 393 b of the fourth on-off valve 304 and the openingportion of the axial through-hole 384 of the fourth on-off valve supportmember 380, is referred to as a third switch state.

In addition, a state where the current which is equal to or greater thanthe fourth reference current is supplied to the coil 321, the firston-off valve back pressure chamber B1 and the reservoir chamber 40 donot communicate with each other via the groove 305 a of the controlvalve 305, the third on-off valve 303 blocks the opening portion of theaxial through-hole 384 of the fourth on-off valve support member 380, isreferred to as a fourth switch state. In the fourth switch state, aswill be described later, the fourth on-off valve 304 is separated fromthe seal member 314.

Operation of Front Fork 21

In the front fork 21 configured as described above, the front wheel sidespring 500 supports weight of the motorcycle 1 and absorbs shock, andthe damping force generation unit 130 damps vibration of the front wheelside spring 500.

FIG. 8 is a view illustrating the operation of the front fork 21 duringa compression stroke.

When the front fork 21 undergoes the compression stroke, the piston 131of the damping force generation unit 130 moves upward with respect tothe cylinder 230 as illustrated by the white arrow, and due to themovement of the piston 131, oil in the first oil chamber 51 is pressed,and oil pressure increases. As a result, the first through-hole 132 isblocked, the lower end side valve 137 is opened, and the oil flows intothe second oil chamber 52 via the first through-hole 132 (refer to arrowC1). The flow of the oil from the first oil chamber 51 to the second oilchamber 52 is restricted by the first through-hole 132 and the lower endside valve 137 such that a damping force is obtained during thecompression stroke.

Since the rod 150 enters the cylinder 230 during the compression stroke,a volume of oil corresponding to the extent of the entry of the rod issupplied to the jack chamber 60 or the reservoir chamber 40 inaccordance with a switch state of the front wheel side flow pathswitching unit 300 (refer to arrow C2). The supply of oil to either ofthe jack chamber 60 and the reservoir chamber 40 in accordance with aswitch state of the front wheel side flow path switching unit 300 willbe described later. The damping force generation unit 130, the rod 150,the cylinder 230, and the like work as a pump that supplies the oil inthe cylinder 230 to the jack chamber 60 or the reservoir chamber 40.Hereinafter, this pump may be referred to as a “pump 600”.

FIG. 9 is a view illustrating the operation of the front fork 21 duringan extension stroke.

When the front fork 21 undergoes the extension stroke, the piston 131 ofthe damping force generation unit 130 moves downward with respect to thecylinder 230 as illustrated by the white arrow, and due to the movementof the piston 131, oil in the second oil chamber 52 is pressed, and oilpressure increases. As a result, the second through-hole 133 is blocked,the upper end side valve 136 is opened, and the oil flows into the firstoil chamber 51 via the second through-hole 133 (refer to arrow T1). Theflow of the oil from the second oil chamber 52 to the first oil chamber51 is restricted by the second through-hole 133 and the upper end sidevalve 136 such that a damping force is obtained during the extensionstroke.

Since the rod 150 is pulled out of the cylinder 230 during the extensionstroke, a volume of oil corresponding to the extent of the rod beingpulled out is supplied from the reservoir chamber 40 to the first oilchamber 51. That is, oil in the reservoir chamber 40 enters the firstoil chamber 51 the pressure of which has become low due to the downwardmovement of the piston 131. That is, the oil in the reservoir chamber 40enters the axial recess portion 161 a of the rod holding member 160 viathe communication hole 182 of the support-member holding member 180, andthe radial through-hole 161 c of the rod holding member 160, moves theball 166 upward, and then enters the inside of the rod 150 (refer toarrow T2). The oil, which has entered the inside of the rod 150, reachesthe first oil chamber 51 via the recess portion 143 and the radialthrough-hole 144 of the piston bolt 140, and the inclination directionthrough-hole 148 of the nut 145 (refer to arrow T3). In addition, sincethe plate valve 149 which covers the opening portion of the inclinationdirection through-hole 148 is provided on the lower end side of the nut145, it is prevented that the oil flows back to the inside of the rod150 from the first oil chamber 51.

In this manner, the communication hole 182 of the support-member holdingmember 180, the radial through-hole 161 c of the rod holding member 160,the axial recess portion 161 a of the rod holding member 160, the innerportion of the rod 150, the recess portion 143 of the piston bolt 140,the radial through-hole 144, and the inclination direction through-hole148 of the nut 145 function as a suction passage which suctions the oilto the inside of the cylinder 230 (first oil chamber 51) from thereservoir chamber 40. In addition, the ball 166 functions as a checkvalve that allows inflow of the oil to the inside of the rod 150 fromthe reservoir chamber 40 and suppresses discharge of the oil to thereservoir chamber 40 from the inside of the rod 150. Hereinafter, theball 166 is referred to as a “suction side check valve Vc”.

Flow State of Oil in Accordance with Switch State of Front Wheel SideFlow Path Switching Unit 300

FIG. 10 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit 300 is in the first switchstate.

In a case where the front wheel side flow path switching unit 300 is inthe first switch state during the compression stroke of the front fork21, as illustrated by arrow P1 in FIG. 10, oil discharged by the pump600 which is configured with the damping force generation unit 130, therod 150, the cylinder 230, and the like flows upward through an axialcommunication hole 351 formed in the unit main body 330. As illustratedin FIG. 7A, the oil of the first on-off valve back pressure chamber B1is discharged to the outside of the unit main body 330 through the siderecess portion 342 b of the unit main body 330, the groove 305 a of thecontrol valve 305, and the first radial communication hole 349 a of theunit main body 330. In addition, as illustrated by an arrow P1 in FIG.10, the oil discharged to the outside of the unit main body 330 isoriented toward the reservoir chamber 40 through the gap between thecut-out portion 348 a of the unit main body 330 and the support member400, that is, through the flow path 41 formed between the protrusionportion 260 b of the base member 260 and the lower end portion of thesupport member 400.

In addition, in a case where the front wheel side flow path switchingunit 300 is in the first switch state, since the pressure in the firston-off valve back pressure chamber B1 is low, the oil which isdischarged by the pump 600 and is oriented upward through the axialcommunication hole 351 formed in the unit main body 330 moves the firston-off valve 301 upward, and separates the inclined surface 301 c of thefirst on-off valve 301 from the opening portion of the third columnarrecess portion 346 c of the unit main body 330. In addition, the oilwhich flows through the gap between the inclined surface 301 c of thefirst on-off valve 301 and the unit main body 330 passes through theintersecting-direction communication hole 346 d formed in the unit mainbody 330, and is oriented toward the reservoir chamber 40 through theflow path 41 formed between the protrusion portion 260 b of the basemember 260 and the lower end portion of the support member 400.

In other words, in a case where the front wheel side flow path switchingunit 300 is in the first switch state, the pressure in the first on-offvalve back pressure chamber B1 is not too high to make it difficult forthe oil which is discharged by the pump 600 and is oriented upwardthrough the axial communication hole 351 formed in the unit main body330 to separate the first on-off valve 301 from the unit main body 330.As a result, the oil discharged by the pump 600 is oriented toward thereservoir chamber 40.

In this manner, the axial communication hole 351 of the unit main body330, the intersecting-direction communication hole 346 d, and the flowpath 41 function as the first communication path R1 (refer to FIG. 3)which communicates with the inside of the cylinder 230 and the reservoirchamber 40.

In addition, the axial communication hole 351 of the unit main body 330,the through-hole 301 e of the first on-off valve 301, the side recessportion 342 b of the unit main body 330, the groove 305 a of the controlvalve 305, the first radial communication hole 349 a of the unit mainbody 330, and the flow path 41 function as a first communication pathbypass path R5 which communicates with the inside of the cylinder 230and the reservoir chamber 40. The control valve 305 functions as a valvewhich controls the opening and closing of the first on-off valve 301 byopening and closing the first communication path bypass path R5.

In addition, the side recess portion 342 b, the accommodation portion342 a, and the first radial communication hole 349 a which are formed inthe unit main body 330 function as a discharge flow path through whichthe oil is oriented toward the reservoir chamber 40 from the firston-off valve back pressure chamber B1. The control valve 305 functionsas a valve which controls the opening and closing of the first on-offvalve 301 by opening and closing the discharge flow path.

FIG. 11 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit 300 is in the second switchstate.

In a case where the front wheel side flow path switching unit 300 is inthe second switch state during the compression stroke of the front fork21, since the first on-off valve back pressure chamber B1 and thereservoir chamber 40 do not communicate with each other via the groove305 a of the control valve 305, the oil in the first on-off valve backpressure chamber B1 is not oriented toward the reservoir chamber 40through the groove 305 a of the control valve 305. Meanwhile, the axialcommunication hole 351 formed in the unit main body 330 and the firston-off valve back pressure chamber B1 communicate with each other viathe through-hole 301 e of the first on-off valve 301.

Therefore, in a case where the front wheel side flow path switching unit300 is in the second switch state, the pressure in the first on-offvalve back pressure chamber B1 is not too high to make it difficult forthe oil which is discharged by the pump 600 and is oriented upwardthrough the axial communication hole 351 of the unit main body 330 tomove the first on-off valve 301 upward (open the first on-off valve301).

In this manner, in a case where the front wheel side flow path switchingunit 300 is in the second switch state, since the first on-off valve 301closes the first communication path R1, as illustrated by an arrow P2illustrated in FIG. 11, the oil discharged by the pump 600 is orientedtoward the jack chamber 60. In other words, the oil which is dischargedby the pump 600 and passes through the axial through-hole 372 a of thesecond on-off valve support member 370 pushes up the second on-off valve302 against the biasing force of the second coil spring 312, and isoriented upward through the gap between the outer circumferentialsurface of the fourth on-off valve support member 380 and the innercircumferential surface of the unit main body 330. In addition, the oilwhich is oriented upward through the gap between the outercircumferential surface of the fourth on-off valve support member 380and the inner circumferential surface of the unit main body 330 isoriented toward the outer side of the unit main body 330 through thethird radial communication hole 357 of the unit main body 330. Afterthis, the oil which passes through the third radial communication hole357 is oriented toward the jack chamber 60 through the annular flow path61 formed between the outer circumferential surface of the cylinder 230and the inner circumferential surface of the base member 260 of thefront wheel side spring-length changing unit 250.

In this manner, the axial through-hole 372 a of the second on-off valvesupport member 370, the gap between the outer circumferential surface ofthe fourth on-off valve support member 380 and the inner circumferentialsurface of the unit main body 330, the third radial communication hole357 of the unit main body 330, and the annular flow path 61 function asthe second communication path R2 (refer to FIG. 3) which communicateswith the inside of the cylinder 230 and the jack chamber 60. The secondon-off valve 302 is also a check valve which allows the flow of the oilto the jack chamber 60 from the inside of the cylinder 230, and whichinterrupts the flow of the oil to the inside of the cylinder 230 fromthe jack chamber 60.

In addition, in a case where the front wheel side flow path switchingunit 300 is in the second switch state, the third on-off valve 303blocks the opening portion of the second through-hole 393 b of thefourth on-off valve 304. Therefore, a space S1 surrounded by the innercircumferential surface of the cylindrical portion 381 of the fourthon-off valve support member 380, the lower end surface of the secondcolumnar portion 392 of the fourth on-off valve 304, and the upper endsurface of the inward portion 382 of the fourth on-off valve supportmember 380, and the jack chamber 60 communicate with each other via theaxial through-hole 384 of the fourth on-off valve support member 380 ora spherical gap between on second on-off valve 302 and the other secondon-off valve 302.

In addition, a space S2 which is between the inner circumferentialsurface of the cylindrical portion 381 of the fourth on-off valvesupport member 380 and the outer circumferential surface of the firstcolumnar portion 391 of the fourth on-off valve 304, and the jackchamber 60 communicate with each other via the radial communication hole385 of the fourth on-off valve support member 380.

As a result, the pressure of the oil in the space S1 which is oil thatapplies an upward force to the fourth on-off valve 304 is the same asthe pressure of the oil in the space S2 which is oil that applies adownward force to the fourth on-off valve 304. In addition, in thefourth on-off valve 304, since a pressure-receiving area A1 (an area ofthe lower end surface of the second columnar portion 392) which receivesthe pressure of the oil in the space S1 is greater than apressure-receiving area A2 (an area of the upper end surface of thesecond columnar portion 392) which receives the pressure of the oil inthe space S2, the fourth on-off valve 304 is maintained to be in contactwith the seal member 314.

FIG. 12 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit 300 is in the third switchstate.

In a case where the front wheel side flow path switching unit 300 is inthe third switch state, as illustrated by an arrow P3 in FIG. 12, theoil in the jack chamber 60 is oriented toward the reservoir chamber 40.In other words, the oil in the jack chamber 60 is oriented downwardthrough the annular flow path 61 formed between the outercircumferential surface of the cylinder 230 and the innercircumferential surface of the base member 260 of the front wheel sidespring-length changing unit 250, the third radial communication hole 357of the unit main body 330, and the gap between the outer circumferentialsurface of the fourth on-off valve support member 380 and the innercircumferential surface of the unit main body 330, and enters a gap G1between the inner circumferential surface of the upper end sidecylindrical portion 371 of the second on-off valve support member 370and the outer circumferential surface of the columnar portion 383 of thefourth on-off valve support member 380. In addition, the oil in the gapG1 is oriented upward through the spherical gap between one secondon-off valve 302 and the other second on-off valve 302, the axialthrough-hole 384 of the fourth on-off valve support member 380, the gapbetween the third on-off valve 303 and the fourth on-off valve 304, andthe gap between the inner circumferential surface of the secondthrough-hole 393 b of the fourth on-off valve 304 and the outercircumferential surface of the push rod 316. The oil which is orientedupward is oriented toward the reservoir chamber 40 through the secondradial communication hole 349 b of the unit main body 330, and the flowpath 41 formed between the protrusion portion 260 b of the base member260 and the lower end portion of the support member 400.

In this manner, the annular flow path 61, the third radial communicationhole 357 of the unit main body 330, the gap between the outercircumferential surface of the fourth on-off valve support member 380and the inner circumferential surface of the unit main body 330, theaxial through-hole 384 of the fourth on-off valve support member 380,the gap between the third on-off valve 303 and the fourth on-off valve304, the gap between the inner circumferential surface of the secondthrough-hole 393 b of the fourth on-off valve 304 and the outercircumferential surface of the push rod 316, the second radialcommunication hole 349 b of the unit main body 330, and the flow path 41function as the third communication path R3 (refer to FIG. 3) whichcommunicates with the jack chamber 60 and the reservoir chamber 40. Inaddition, the third on-off valve 303 opens and closes the thirdcommunication path R3.

In addition, the annular flow path 61, the third radial communicationhole 357 of the unit main body 330, the gap between the outercircumferential surface of the fourth on-off valve support member 380and the inner circumferential surface of the unit main body 330, and theaxial through-hole 384 of the fourth on-off valve support member 380which are on the upstream side of the space S1 in the thirdcommunication path R3 function as an inflow path which is orientedtoward the space S1 from the jack chamber 60. The third on-off valve 303also opens and closes the inflow path.

In addition, in a case where the front wheel side flow path switchingunit 300 is in the third switch state, the third on-off valve 303 isseparated from the opening portion of the second through-hole 393 b suchthat a gap G2 between the third on-off valve 303 and the opening portionof the second through-hole 393 b of the fourth on-off valve 304 becomesthe smallest restriction portion in the third communication path R3. Ina state where the third on-off valve 303 is separated from the openingportion of the second through-hole 393 b, the pressure of the oil in thespace S1 which applies the upward force to the fourth on-off valve 304is smaller than the pressure of the oil in the space S2 which is oilthat applies the downward force to the fourth on-off valve 304, but thepressure-receiving area A1 is greater than the pressure-receiving areaA2, and thus, the fourth on-off valve 304 is maintained to be in contactwith the seal member 314 (pressure of oil in the spaceS1×pressure-receiving area A1>pressure of oil in the spaceS2×pressure-receiving area A2).

In other words, in a case where the front wheel side flow path switchingunit 300 is in the third switch state, the fourth on-off valve 304 isset as follows to be maintained to be in contact with the seal member314. In other words, the third reference amount is set so that the gapG2 becomes the smallest restriction portion by further reducing a flowpath area formed by the gap G2 to be smaller than a flow path area (thesmallest area of the inflow path) of the axial through-hole 384 of thefourth on-off valve support member 380 or an area (the smallest area ofthe flow path downstream of the gap G2) of the flow path formed by a gapG3 between the outer circumferential surface of the second shaft portion318 of the push rod 316 and the inner circumferential surface of thesecond through-hole 393 b of the fourth on-off valve 304. In addition,the third reference amount is set considering the pressure-receivingarea A1 and the pressure-receiving area A2 so that a value obtained bymultiplying the pressure of the oil in the space S1 that becomes smallas the third on-off valve 303 is open by the pressure-receiving area A1becomes greater than a value obtained by multiplying the pressure of theoil in the space S2 by the pressure-receiving area A2 (pressure of oilin the space S1×pressure-receiving area A1>pressure of oil in the spaceS2×pressure-receiving area A2).

FIG. 13 is a view illustrating a flow state of oil in a case where thefront wheel side flow path switching unit 300 is in the fourth switchstate.

In a case where the front wheel side flow path switching unit 300 is inthe fourth switch state, since the third on-off valve 303 blocks theopening portion of the axial through-hole 384 of the fourth on-off valvesupport member 380, the inflow of the oil into the space S1 that appliesthe upward force to the fourth on-off valve 304 is small or the oil doesnot flow into the space S1. Therefore, even when the pressure of the oilin the space S1 is smaller than that of a case where the front wheelside flow path switching unit 300 is in the third switch state and thepressure-receiving area A1 is greater than the pressure-receiving areaA2, the downward force applied to the fourth on-off valve 304 is greaterthan the upward force (pressure of oil in the spaceS1×pressure-receiving area A1<pressure of oil in the spaceS2×pressure-receiving area A2). As a result, the fourth on-off valve 304is separated from the seal member 314. In addition, as illustrated by anarrow P4 in FIG. 13, the oil in the jack chamber 60 is oriented towardthe reservoir chamber 40 through the gap between the fourth on-off valve304 and the seal member 314. In other words, the oil in the jack chamber60 is oriented toward the reservoir chamber 40 through the annular flowpath 61, the third radial communication hole 357 of the unit main body330, the radial communication hole 385 of the fourth on-off valvesupport member 380, the gap between the fourth on-off valve 304 and theseal member 314, the second radial communication hole 349 b of the unitmain body 330, the flow path 41 formed between the protrusion portion260 b of the base member 260 and the lower end portion of the supportmember 400.

In this manner, the annular flow path 61, the third radial communicationhole 357 of the unit main body 330, the radial communication hole 385 ofthe fourth on-off valve support member 380, the gap between the fourthon-off valve 304 and the seal member 314, the second radialcommunication hole 349 b of the unit main body 330, and the flow path 41function as the fourth communication path R4 (refer to FIG. 3) whichcommunicates with the jack chamber 60 and the reservoir chamber 40. Inaddition, the fourth on-off valve 304 opens and closes the fourthcommunication path R4.

Regarding Raising and Lowering Vehicle Height

In a case where the front wheel side flow path switching unit 300 is inthe second switch state, during the compression stroke of the front fork21 that operates as described above, the oil discharged by the pump 600flows into the jack chamber 60, and the amount of oil in the jackchamber 60 increases. Due to an increase in amount of oil in the jackchamber 60, the upper end portion support member 270 moves downward withrespect to the base member 260 of the front wheel side spring-lengthchanging unit 250. When the spring length of the front wheel side spring500 decreases due to the downward movement of the upper end portionsupport member 270 with respect to the base member 260, a spring forceof the front wheel side spring 500 pushing the upper end portion supportmember 270 increases compared to that before the upper end portionsupport member 270 moves with respect to the base member 260. As aresult, even when a force acts on the front wheel 2 side from thevehicle body frame 11, an initial set load (preload) at which relativepositions both of the front wheel 2 and the vehicle body frame 11 arenot changed, increases. In this case, in a case where the same forceacts on the front wheel 2 from the vehicle body frame 11 (a seat 19)side in the axial direction, the amount of compression of the front fork21 decreases. Therefore, when the spring length of the front wheel sidespring 500 decreases due to the movement of the upper end portionsupport member 270 with respect to the base member 260, the height ofthe seat 19 is raised (the vehicle height is raised) as compared to thatbefore the upper end portion support member 270 moves with respect tothe base member 260.

On the other hand, in a case where the front wheel side flow pathswitching unit 300 is in the third switch state or in the fourth switchstate, the amount of oil in the jack chamber 60 decreases. Thereby, theupper end portion support member 270 moves upward with respect to thebase member 260 of the front wheel side spring-length changing unit 250.When the spring length of the front wheel side spring 500 increases dueto the upward movement of the upper end portion support member 270 withrespect to the base member 260, a spring force of the front wheel sidespring 500 pushing the upper end portion support member 270 decreases ascompared to that before the upper end portion support member 270 moveswith respect to the base member 260. In this case, the initial set load(preload) decreases, and in a case where the same force acts from thevehicle body frame 11 (the seat 19) in the axial direction, the amountof compression of the front fork 21 increases. Therefore, when thespring length of the front wheel side spring 500 increases due to theupward movement of the upper end portion support member 270 with respectto the base member 260, the height of the seat 19 is lowered (thevehicle height is lowered) as compared to that before the upper endportion support member 270 moves with respect to the base member 260.When the front wheel side flow path switching unit 300 is in the fourthswitch state, the amount of oil in the jack chamber 60 decreases morequickly than that in a case of the third switch state, and thus, thevehicle height is lowered more quickly than in the third switch state.

In a case where the front wheel side flow path switching unit 300 is inthe first switch state, the oil discharged by the pump 600 during thecompression stroke flows into the reservoir chamber 40, and thus, theamount of oil in the jack chamber 60 neither increases nor decreases.Hence, the height of the seat 19 is maintained (the vehicle height ismaintained).

In this manner, the front wheel side flow path switching unit 300according to the embodiment can open any communication path among thefirst communication path R1, the second communication path R2, and thethird communication path R3, in accordance with the amount of suppliedcurrent. In other words, the front wheel side flow path switching unit300 can raise the vehicle height, lower the vehicle height, or maintainthe vehicle height by suppressing the axial movement amount of theoperation rod 324 of the front wheel side solenoid 320, in accordancewith the amount of supplied current. In other words, the front wheelside flow path switching unit 300 configured as a single unit cancontrol three control modes in accordance with the amount of current: araising mode in which the vehicle height is raised; a lowering mode inwhich the vehicle height is lowered; and a maintaining mode in which thevehicle height is maintained. In addition, in the lowering mode, thefront wheel side flow path switching unit 300 can realize a slowlowering mode in which the vehicle height can be slowly lowered; and aquick lowering mode in which the vehicle height is quickly lowered.

In addition, the front wheel side flow path switching unit 300 whichrealizes the above-described function is configured to be attached tothe upper end portion of the cylinder 230 on the inner side of the innertube 210. In other words, the front wheel side flow path switching unit300 is not disposed on the outer side of the inner tube 210. Inaddition, the front wheel side flow path switching unit 300 does notrequire a plurality of electromagnetic actuators (solenoids or the like)so as to realize the three control modes. Hence, according to the frontwheel side flow path switching unit 300 according to the embodiment, itis possible to reduce a mounting space by simplifying the configurationof the front fork 21, and to realize the aforementioned function. Inother words, the front fork 21 can switch between the three controlmodes without an increase in size by employing the front wheel side flowpath switching unit 300 according to the embodiment to the front fork 21which has a limited surrounding space.

The front wheel side flow path switching unit 300 according to theembodiment is placed in the maintaining mode in a case where the currentto be supplied is less than the first reference current, the raisingmode in a case where the current to be supplied is equal to or greaterthan the first reference current and is less than the second referencecurrent, and the lowering mode in a case where the current to besupplied is equal to or greater than the second reference current. Inother words, the front wheel side flow path switching unit 300sequentially transitions from the maintaining mode, to the raising mode,and to the lowering mode in accordance with the increase in amount ofcurrent to be supplied.

In this manner, the front wheel side flow path switching unit 300according to the embodiment does not sequentially transition from themaintaining mode, to the lowering mode, and to the raising mode inaccordance with the increase in amount of current to be supplied. In acase where the front wheel side flow path switching unit 300 isconfigured to transition from the maintaining mode, to the loweringmode, and to the raising mode, when the amount of current is decreasedso as to maintain a raised vehicle height, there is a concern that theamount of current is adjusted to the amount of current corresponding tothe lower mode, and the vehicle height is lowered.

Meanwhile, since the front wheel side flow path switching unit 300according to the embodiment sequentially transitions from themaintaining mode, to the raising mode, and to the lowering mode inaccordance with the increase in the amount of current to be supplied,even when the amount of current is decreased so as to maintain a raisedvehicle height, the vehicle height is not lowered.

The front wheel side flow path switching unit 300 which is an example ofa flow path control device according to the embodiment as describedabove includes the first on-off valve 301 which is an example of a firstvalve, and the unit main body 330 which is an example of a flow pathforming member. The first on-off valve 301 opens and closes the firstcommunication path R1 which is an example of a first flow path. In thefirst communication path R1, the supplied oil is oriented toward thereservoir chamber 40 which is an example of a first chamber. The unitmain body 330 forms a discharge flow path which is an example of asecond flow path that is oriented toward the reservoir chamber 40 fromthe first on-off valve back pressure chamber B1 which is an example of asecond chamber that accommodates the oil which applies the force in thedirection in which the first on-off valve 301 is closed to the firston-off valve 301. The unit main body 330 is formed with theaccommodation portion 342 a, the first radial communication hole 349 a,and the side recess portion 342 b. The accommodation portion 342 a is anexample of a first recess portion and is recessed from the first on-offvalve back pressure chamber B1. The first radial communication hole 349a is an example of a communication path and communicates with theaccommodation portion 342 a and the reservoir chamber 40. The siderecess portion 342 b is an example of a second recess portion and isrecessed from the first on-off valve back pressure chamber B1 so as tobe continuous to the accommodation portion 342 a and not to becontinuous to the first radial communication hole 349 a. The unit mainbody 330 forms the discharge flow path which is an example of a secondflow path that is oriented toward the reservoir chamber 40 from thefirst on-off valve back pressure chamber B1 via the first radialcommunication hole 349 a and the side recess portion 342 b. Then, thefront wheel side flow path switching unit 300 includes the control valve305 which is an example of a second valve. The control valve 305 isformed with the groove 305 a which is recessed from the outer surface.The control valve 305 is fitted to the accommodation portion 342 a ofthe unit main body 330. The control valve 305 opens and closes thedischarge flow path which is an example of a second flow path by movingbetween (i) the position at which the groove 305 a communicates with theside recess portion 342 b and the first radial communication hole 349 aand (ii) the position at which the groove 305 a does not communicatewith the side recess portion 342 b and the first radial communicationhole 349 a.

According to the front wheel side flow path switching unit 300configured as described above, in a case where the control valve 305 isat the position at which the groove 305 a communicates with the siderecess portion 342 b and the first radial communication hole 349 a, thepressure in the first on-off valve back pressure chamber B1 decreasessince the oil in the first on-off valve back pressure chamber B1 isoriented toward the reservoir chamber 40. As a result, the force in thedirection in which the first on-off valve 301 is closed decreases, thefirst on-off valve 301 is open, and the oil supplied from the pump 600is oriented toward the reservoir chamber 40.

Meanwhile, in a case where the control valve 305 is positioned at aposition at which the groove 305 a does not communicate with the siderecess portion 342 b and the first radial communication hole 349 a, thepressure in the first on-off valve back pressure chamber B1 is highsince the oil in the first on-off valve back pressure chamber B1 isunlikely to be oriented toward the reservoir chamber 40. As a result,the force in the direction in which the first on-off valve 301 is closedincreases, the first on-off valve 301 is closed, and the oil suppliedfrom the pump 600 is unlikely to be oriented toward the reservoirchamber 40. According to the front wheel side flow path switching unit300 according to the embodiment, since it is possible to control theopening and closing of the first on-off valve 301 by suppressing theposition of the control valve 305, it is possible to control whether ornot the oil supplied from the pump 600 is oriented toward the reservoirchamber 40 with high accuracy. Therefore, for example, even when a largeamount of oil is discharged by the pump due to rapid vibration of thefront wheel 2 by reducing the interval of roughness of a road surface ora large amplitude of vibration of the front wheel 2 by increasingroughness of a road surface, it is possible to control whether or notthe oil supplied from the pump 600 is oriented toward the reservoirchamber 40 with high accuracy, and thus, it is possible to control theamount of oil in the jack chamber 60 with high accuracy.

Here, the side recess portion 342 b of the unit main body 330 may berecessed in the same direction as the moving direction of the controlvalve 305, and the first radial communication hole 349 a may be formedin the direction intersecting with the moving direction of the controlvalve 305. Accordingly, it is possible to easily control whether or notthe side recess portion 342 b and the first radial communication hole349 a communicate with each other by moving the control valve 305 withhigh accuracy.

In addition, in the moving direction of the control valve 305, the siderecess portion 342 b and the first radial communication hole 349 a maycommunicate with each other in a case where the groove 305 a of thecontrol valve 305 overlap the first radial communication hole 349 a ofthe unit main body 330, and the side recess portion 342 b and the firstradial communication hole 349 a may not communicate with each other in acase where the groove 305 a does not overlap the first radialcommunication hole 349 a. Accordingly, it is possible to easily controlthe opening and closing of the first on-off valve 301 according towhether or not the position of the groove 305 a of the control valve 305matches the position of the first radial communication hole 349 a of theunit main body 330.

FIG. 14 is a view illustrating a positional relationship between theouter circumferential surface of the control valve 305 and the openingportion of a first radial communication hole 349 a in a case where thegroove 305 a is at a position which does not communicate with the siderecess portion 342 b and the first radial communication hole 349 a.

The control valve 305 may have a columnar shape and move in an axialdirection of the columnar shape. When viewed in the moving direction ofthe control valve 305, the first radial communication hole 349 a of theunit main body 330 may be formed on the side opposite to the side recessportion 342 b across the center of the control valve 305. Accordingly,the force which is oriented toward the first radial communication hole349 a is applied to the control valve 305 by the oil in the side recessportion 342 b. As a result, in particular, in a case where the positionof the control valve 305 in the moving direction is the position atwhich the groove 305 a does not overlap the first radial communicationhole 349 a, as illustrated in FIG. 14, the outer surface of the controlvalve 305 blocks the opening portion of the first radial communicationhole 349 a. Therefore, for example, even in a case of a dimensionalrelationship in which the inner surface of the accommodation portion 342a is greater than the outer surface of the control valve 305 and a gapis generated between the outer surface of the control valve 305 and theinner surface of the accommodation portion 342 a, it is possible tomaintain high pressure in the first on-off valve back pressure chamberB1 since the oil in the first on-off valve back pressure chamber B1 isunlikely to be oriented toward the reservoir chamber 40.

In addition, when the force oriented toward first radial communicationhole 349 a is applied to the control valve 305 by the oil in the siderecess portion 342 b, the first radial communication hole 349 a and theside recess portion 342 b may not be formed to be opposite to each otheracross the center of the control valve 305. In addition, the controlvalve 305 may have a shape of a square column.

As described above, the front wheel side flow path switching unit 300which is an example of a flow path control device according to theembodiment includes the fourth on-off valve 304 which is an example of afirst valve. The fourth on-off valve 304 transitions from a closed statein which the fourth communication path R4 which is an example of a firstflow path and which is oriented from the jack chamber 60 which is anexample of a first chamber toward the reservoir chamber 40 which is anexample of a second chamber is closed to an open state in which thefourth communication path R4 is open by moving from the closed state tothe space S1 which is an example of a third chamber. The fourth on-offvalve 304 is formed with the axial through-hole 393 which is an exampleof a communication path and which communicates with the fourthcommunication path R4 and the space S1. The pressure-receiving area A1which is an example of a first pressure-receiving area and to which thepressure in the jack chamber 60 is applied in the closed state issmaller than the pressure-receiving area A2 which is an example of asecond pressure-receiving area and to which the pressure in the space S1is applied. In addition, the front wheel side flow path switching unit300 includes the third on-off valve 303 which is an example of a secondvalve. The third on-off valve 303 is provided in the space S1 on thethird communication path R3 which is an example of the second flow path.The third communication path R3 is oriented from the jack chamber 60toward the reservoir chamber 40 through the axial through-hole 393 ofthe fourth on-off valve 304. The third on-off valve 303 transitionsbetween (i) a first state where the axial through-hole 393 is closed andthe inflow path oriented from the jack chamber 60 toward the space S1 isopen and (ii) a second state where the inflow path is closed and theaxial through-hole 393 is open.

According to the front wheel side flow path switching unit 300configured as described above, in a case of the first state where thethird on-off valve 303 closes the axial through-hole 393 of the fourthon-off valve 304 and opens the inflow path that reaches the space S1from the jack chamber 60, the jack chamber 60 and the space S1 which isa back pressure chamber of the fourth on-off valve 304 have the samepressure. Then, since the pressure-receiving area A1 of the fourthon-off valve 304 to which the pressure of the jack chamber 60 is appliedin the closed state is smaller than the pressure-receiving area A2 towhich the pressure in the space S1 is applied, the fourth on-off valve304 is placed in the closed state. Since the third on-off valve 303closes the axial through-hole 393 of the fourth on-off valve 304, thethird communication path R3 is also closed. Therefore, the oil in thejack chamber 60 does not reach the reservoir chamber 40.

On the other hand, in a case of the second state where the third on-offvalve 303 closes the inflow path that reaches the space S1 from the jackchamber 60 and opens the axial through-hole 393 of the fourth on-offvalve 304, the oil is not supplied to the space S1 which is the backpressure chamber of the fourth on-off valve 304. Thus, the pressurebecomes lower than that of the jack chamber 60. Therefore, the fourthon-off valve 304 is likely to move to the space S1, and the fourthon-off valve 304 is likely to be open. Then, in the front wheel sideflow path switching unit 300 according to the embodiment, in a casewhere the third on-off valve 303 is in the second state, the fourthon-off valve 304 is set to be in the open state. As a result, the oil inthe jack chamber 60 is likely to reach the reservoir chamber 40 throughthe fourth communication path R4.

With the front wheel side flow path switching unit 300 according to theembodiment, it is possible to control the opening and closing of thefourth on-off valve 304 by controlling the opening and closing of thethird on-off valve 303. Thus, it is possible to control whether or notthe oil in the jack chamber 60 is oriented toward the reservoir chamber40 with high accuracy.

Here, the third on-off valve 303 may transition to the third state wherethe axial through-hole 393 and the inflow path are open such that thegap G2 between the third on-off valve 303 and the opening portion of theaxial through-hole 393 of the fourth on-off valve 304 becomes thesmallest restriction portion of the third communication path R3. In acase where the third on-off valve 303 is in the third state, the axialthrough-hole 393 of the fourth on-off valve 304 and the inflow path areopen. Thus, the third communication path R3 is open, and the oil in thejack chamber 60 reaches the reservoir chamber 40 through the thirdcommunication path R3. In addition, the pressure in the space S1 whichis the back pressure chamber of the fourth on-off valve 304 becomeslower than that of the jack chamber 60. However, since the gap G2between the third on-off valve 303 and the opening portion of the axialthrough-hole 393 of the fourth on-off valve 304 is the smallestrestriction portion of the third communication path R3, the pressure inthe space S1 is higher than that of the axial through-hole 393 of thefourth on-off valve 304. Therefore, the position of the fourth on-offvalve 304 is determined by the size of the pressure-receiving area A1 ofthe fourth on-off valve 304 to which the pressure of the jack chamber 60is applied in the closed state and the size of the pressure-receivingarea A2 to which the pressure in the space S1 is applied.

Then, in a case where the third on-off valve 303 is in the third state,the pressure-receiving area A2 of the fourth on-off valve 304 may begreater than the pressure-receiving area A1 such that the fourth on-offvalve 304 is closed. Accordingly, in a case where the third on-off valve303 is in the third state, while the fourth on-off valve 304 is in theclosed state, the oil in the jack chamber 60 can reach the reservoirchamber 40 only through the third communication path R3. Then, byreducing the flow path area of the third communication path R3 to besmaller than the flow path area of the fourth communication path R4, itis possible to reduce the speed by which the oil in the jack chamber 60reaches the reservoir chamber 40 in a case where the third on-off valve303 is in the third state as compared with a case where the third on-offvalve 303 is in the second state. In addition, as the fourth on-offvalve 304 is in the closed state in a case where the third on-off valve303 is in the third state, it is possible to more rapidly change from astate where the amount of oil in the jack chamber 60 is reduced and thevehicle height is low to a state where the amount of oil in the jackchamber 60 is maintained and the vehicle height is maintained, in a casewhere the third on-off valve 303 is in the third state as compared witha case where the fourth on-off valve 304 is in an open state.

The front fork 21 which is an example of a vehicle height adjustmentapparatus according to embodiment as described above includes the spring500, the spring-length changing unit 250 which is an example of achanging device, the first on-off valve 301 which is an example of afirst valve, the control valve 305 which is an example of a backpressure adjustment valve, and the second on-off valve 302. One end ofthe spring 500 is supported on the vehicle body side. The other end ofthe spring 500 is supported on the wheel side. The spring-lengthchanging unit 250 changes the length of the spring 500 in accordancewith the amount of oil in the jack chamber 60 which is an example of theaccommodation chamber that accommodates the oil. The first on-off valve301 opens and closes the first communication path R1 which is an exampleof a first flow path. In the first flow path, the oil supplied from thepump 600 is oriented toward the reservoir chamber 40 which is an exampleof a storage chamber. The control valve 305 opens and closes thedischarge flow path oriented toward the reservoir chamber 40 from thefirst on-off valve back pressure chamber B1 which is an example of aback pressure chamber. The first on-off valve back pressure chamber B1accommodates oil that applies the force in the direction in which thefirst on-off valve 301 is closed to the first on-off valve 301. Thesecond on-off valve 302 opens and closes the second communication pathR2 which is an example of a second flow path. In the second flow path,the oil supplied from the pump 600 is oriented toward the jack chamber60 in a case where the first on-off valve 301 is in the closed state.

With the front fork 21 according to the embodiment configured asdescribed above, in a case where the control valve 305 opens thedischarge flow path oriented toward the reservoir chamber 40 from thefirst on-off valve back pressure chamber B1, the pressure in the firston-off valve back pressure chamber B1 is low since the oil in the firston-off valve back pressure chamber B1 is oriented toward the reservoirchamber 40. As a result, the force in the direction in which the firston-off valve 301 is closed decreases, the first on-off valve 301 isopen, and the oil supplied from the pump 600 is oriented toward thereservoir chamber 40. Meanwhile, in a case where the control valve 305closes the discharge flow path oriented toward the reservoir chamber 40from the first on-off valve back pressure chamber B1, the pressure inthe first on-off valve back pressure chamber B1 is high since the oil inthe first on-off valve back pressure chamber B1 is unlikely to beoriented toward the reservoir chamber 40. As a result, the force in thedirection in which the first on-off valve 301 is closed increases, thefirst on-off valve 301 is unlikely to be open, and the oil supplied fromthe pump 600 is unlikely to be oriented toward the reservoir chamber 40.Then, in the front fork 21 according to the embodiment, in a case wherethe first on-off valve 301 is closed, the second on-off valve 302 opensthe second communication path R2. Thus, the oil supplied from the pump600 is oriented toward the jack chamber 60 through the secondcommunication path R2. With the front fork 21 according to theembodiment, it is possible to control the opening and closing of thefirst on-off valve 301 by controlling the position of the control valve305. Thus, it is possible to control whether the oil supplied from thepump 600 is oriented toward the reservoir chamber 40 or is orientedtoward the jack chamber 60, with high accuracy. Therefore, it ispossible to control the length of the spring 500 with high accuracy bycontrolling the position of the control valve 305, and to adjust thevehicle height with high accuracy.

Then, the front fork 21 may further include the unit main body 330 whichis an example of a flow path forming member. The unit main body 330forms the discharge flow path oriented toward the reservoir chamber 40from the first on-off valve back pressure chamber B1 via the upper endside center recess portion 342 which is an example of a recess portionthat is recessed from the first on-off valve back pressure chamber B1.The control valve 305 may be fitted to the upper end side center recessportion 342 of the unit main body 330 to be movable between a positionat which the discharge flow path is open and a position at which thedischarge flow path is closed. Accordingly, it is possible to controlthe pressure in the first on-off valve back pressure chamber B1 withhigh accuracy by controlling the position of the control valve 305, andto control the opening and closing of the first on-off valve 301 withhigh accuracy. As a result, it is possible to adjust the vehicle heightwith high accuracy.

In addition, the front fork 21 may further include the third on-offvalve 303 which is an example of a third valve. The third on-off valve303 opens and closes the third communication path R3 which is an exampleof a third flow path oriented toward the reservoir chamber 40 from thejack chamber 60 by moving in accordance with the position of the controlvalve 305. Accordingly, it is possible to control the position of thethird on-off valve 303 by controlling the position of the control valve305, and to control the opening and closing of the third communicationpath R3 oriented toward the reservoir chamber 40 from the jack chamber60 with high accuracy. Therefore, it is possible to control whether theamount of oil in the jack chamber 60 is reduced by allowing the oil inthe jack chamber 60 to be oriented toward the reservoir chamber 40, orthe amount of oil in the jack chamber 60 is maintained with highaccuracy, and to adjust the vehicle height with high accuracy.

In addition, the front fork 21 may further include the fourth on-offvalve 304 which is an example of a fourth valve. The fourth on-off valve304 opens and closes the fourth communication path R4 which is anexample of a fourth flow path, by moving in accordance with the positionof the third on-off valve 303. The fourth communication path R4 is aflow path oriented toward the reservoir chamber 40 from the jack chamber60. The flow path area of the fourth communication path R4 is greaterthan that of the third communication path R3. Accordingly, it ispossible to control the position of the fourth on-off valve 304 bycontrolling the position of the control valve 305 that controls theposition of the third on-off valve 303, and to control the opening andclosing of the fourth communication path R4 oriented toward thereservoir chamber 40 from the jack chamber 60 with high accuracy.Therefore, it is possible to control whether the amount of oil in thejack chamber 60 rapidly decreases by allowing the oil in the jackchamber 60 to be oriented toward the reservoir chamber 40 through thefourth communication path R4 having a large flow path area, or theamount of oil in the jack chamber 60 slowly decreases by allowing theoil in the jack chamber 60 to be oriented toward the reservoir chamber40 through the third communication path R3 having a small flow patharea, and to adjust the vehicle height with high accuracy.

In addition, the third on-off valve 303 may be provided on the thirdcommunication path R3 and in the space S1 which is an example of afourth valve back pressure chamber that accommodates oil which appliesthe force in the direction in which the fourth on-off valve 304 isclosed to the fourth on-off valve 304. The third on-off valve 303 maymove between a position at which the inflow path that reaches the spaceS1 from the jack chamber 60 is open and a position at which the inflowpath is closed. In a case where the third on-off valve 303 is at aposition at which the inflow path that reaches the space S1 from thejack chamber 60 is closed, the oil is not supplied to the space S1 whichbecomes the back pressure chamber of the fourth on-off valve 304. Thus,the pressure becomes lower than that of the jack chamber 60. Therefore,the fourth on-off valve 304 is likely to move to the space S1, and thefourth on-off valve 304 is likely to be open. Meanwhile, in a case wherethe third on-off valve 303 is at a position at which the inflow path isopen, the oil is supplied to the space S1 which becomes the backpressure chamber of the fourth on-off valve 304. Thus, the pressurebecomes lower than that in a case where the third on-off valve 303 is ata position at which the inflow path is closed. Therefore, the fourthon-off valve 304 is unlikely to move to the space S1, and the fourthon-off valve 304 is unlikely to be open. With the front fork 21according to the embodiment, by controlling the position of the thirdon-off valve 303, it is possible to control the open and closed state ofthe fourth on-off valve 304 with high accuracy.

Modification Example of Control Valve 305

In the control valve 305 according to the above-described embodiment, inorder to perform sequential transition to the maintaining mode, theraising mode, and the lowering mode in order in accordance with theincrease in amount of current to be supplied, a relationship between theamount of protrusion of the operation rod 324 and the position of thegroove 305 a of the control valve 305 is defined. In other words, in acase where the amount of protrusion of the operation rod 324 is lessthan the first reference amount, the position in the axial direction ofthe groove 305 a of the control valve 305 overlaps the first radialcommunication hole 349 a of the unit main body 330, and in a case wherethe amount of protrusion of the operation rod 324 is equal to or greaterthan the first reference amount, the position in the axial direction ofthe groove 305 a becomes a position below the first radial communicationhole 349 a. Meanwhile, in a case where the amount of protrusion of theoperation rod 324 is less than the first reference amount, the positionin the axial direction of the groove 305 a of the control valve 305becomes the position above the first radial communication hole 349 a ofthe unit main body 330, and in a case where the amount of protrusion ofthe operation rod 324 is equal to or greater than the first referenceamount, by forming the groove 305 a such that the position in the axialdirection of the groove 305 a overlaps the first radial communicationhole 349 a, sequential transition from the raising mode, to themaintaining mode, and to the lowering mode in accordance with theincrease in amount of current to be supplied can be performed. In otherwords, only by changing the position of the groove 305 a of the controlvalve 305, it is possible to realize the front wheel side flow pathswitching unit 300 which sequentially transitions from the raising mode,to the maintaining mode, and to the lowering mode.

Modification Example of Front Wheel Side Flow Path Switching Unit 300

A front wheel side solenoid 310 according to the above-describedembodiment generates an axial thrust force to a plunger 313 in such away that the amount of protrusion of an operation rod 314 from the case315 increases to the extent that energization current to a coil 311increases; however, the invention is not particularly limited thereto.For example, the front wheel side solenoid 310 may generate an axialthrust force to the plunger 313 in such a way that the amount ofprotrusion of the operation rod 314 from the case 315 decreases to theextent that energization current to the coil 311 increases. The frontwheel side flow path switching unit 300 with this configuration as asingle unit can control the three control modes according to the amountof current: the raising mode in which the vehicle height is raised; thelowering mode in which the vehicle height is lowered; and themaintaining mode in which the vehicle height is maintained.

In addition, in the above-described embodiment, a configuration in whichthe front wheel side flow path switching unit 300 which can be switchedto three control modes including the raising mode, the lowering mode,and the maintaining mode is employed in the front fork 21 isillustrated, but the invention is not particularly limited. The frontwheel side flow path switching unit 300 according to the above-describedembodiment may be employed in the rear suspension 22.

What is claimed is:
 1. A flow path control device comprising: a firstvalve which opens and closes a first flow path in which a supplied fluidis oriented toward a first chamber; a flow path forming member formedwith a first recess portion which is recessed, along an axial directionof the first recess portion, from a second chamber accommodating thefluid that applies a force to the first valve in a direction in whichthe first valve is closed, a communication path which communicates withthe first recess portion and the first chamber, and a second recessportion which is recessed from the second chamber so as to be continuousto the first recess portion and not to be continuous to thecommunication path, wherein the second recess portion is continuous tothe first recess portion in a radial direction which intersects with theaxial direction, wherein the flow path forming member forms a secondflow path oriented toward the first chamber from the second chamber viathe communication path and the second recess portion; and a second valveformed with a groove which is recessed from an outer surface, whereinthe second valve is fitted to the first recess portion of the flow pathforming member, and wherein the second valve opens and closes the secondflow path by moving between a position at which the groove communicateswith the second recess portion and the communication path and a positionat which the groove does not communicate with the second recess portionand the communication path.
 2. The flow path control device according toclaim 1, wherein the second recess portion of the flow path formingmember is recessed in a direction which is the same as a movingdirection of the second valve, and wherein the communication path isformed in a direction which intersects with the moving direction of thesecond valve.
 3. The flow path control device according to claim 2,wherein the second recess portion and the communication path communicatewith each other in a case where the groove of the second valve overlapsthe communication path of the flow path forming member in the movingdirection of the second valve, and wherein the second recess portion andthe communication path do not communicate with each other in a casewhere the groove does not overlap the communication path.
 4. The flowpath control device according to claim 1, wherein the second valve has acolumnar shape and moves in an axial direction of the columnar shape,and wherein, when viewed in the moving direction of the second valve,the communication path of the flow path forming member is formed on aside opposite to the second recess portion across a center of the secondvalve.
 5. The flow path control device according to claim 2, wherein thesecond valve has a columnar shape and moves in an axial direction of thecolumnar shape, and wherein, when viewed in the moving direction of thesecond valve, the communication path of the flow path forming member isformed on a side opposite to the second recess portion across a centerof the second valve.
 6. The flow path control device according to claim3, wherein the second valve has a columnar shape and moves in an axialdirection of the columnar shape, and wherein, when viewed in the movingdirection of the second valve, the communication path of the flow pathforming member is formed on a side opposite to the second recess portionacross a center of the second valve.
 7. A vehicle height adjustmentapparatus comprising: a first valve which opens and closes a first flowpath in which a fluid supplied from a pump is oriented toward a storagechamber which stores the fluid; a flow path forming member formed with afirst recess portion which is recessed, along an axial direction of thefirst recess portion, from a back pressure chamber accommodating thefluid that applies a force to the first valve in a direction in whichthe first valve is closed, a communication path which communicates withthe first recess portion and the storage chamber, and a second recessportion which is recessed from the back pressure chamber so as tocommunicate with the first recess portion and so as not to communicatewith the communication path, wherein the second recess portion iscontinuous to the first recess portion in a radial direction whichintersects with the axial direction, wherein the flow path formingmember forms a second flow path oriented toward the storage chamber fromthe back pressure chamber via the communication path and the secondrecess portion; and a second valve formed with a groove recessed from anouter surface, wherein the second valve is accommodated in the firstrecess portion of the flow path forming member, and wherein the secondvalve opens and closes the second flow path by moving between a positionat which the groove communicates with the second recess portion and thecommunication path and a position at which the groove does notcommunicate with the second recess portion and the communication path.8. The vehicle height adjustment apparatus according to claim 7, furthercomprising: a spring, wherein one end of the spring is supported on avehicle body side, and the other end of the spring is supported on awheel side; and a changing device which changes a length of the springin accordance with an amount of the fluid in an accommodation chamberthat accommodates the fluid, wherein, in a case where the second valvecloses the second flow path, the first valve is closed and the fluidsupplied from the pump is supplied to the accommodation chamber.